Center for Quantum Devices - Most Downloaded Journal Articles

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18.	GaN-based nanostructured photodetectors J.L. Pau, C. Bayram, P. Giedraitis, R. McClintock, and M. Razeghi SPIE Proceedings, San Jose, CA Volume 7222-14-- January 26, 2009 ...[Visit Journal] The use of nanostructures in semiconductor technology leads to the observation of new phenomena in device physics. Further quantum and non-quantum effects arise from the reduction of device dimension to a nanometric scale. In nanopillars, quantum confinement regime is only revealed when the lateral dimensions are lower than 50 nm. For larger mesoscopic systems, quantum effects are not observable but surface states play a key role and make the properties of nanostructured devices depart from those found in conventional devices. In this work, we present the fabrication of GaN nanostructured metal-semiconductor-metal (MSM) and p-i-n photodiodes (PIN PDs) by e-beam lithography, as well as the investigation of their photoelectrical properties at room temperature. The nanopillar height and diameter are about 520 nm and 200 nm, respectively. MSMs present dark currents densities of 0.4 A/cm² at ±100 V. A strong increase of the optical response with bias is observed, resulting in responsivities higher than 1 A/W. The relationship between this gain mechanism and surface states is discussed. PIN PDs yield peak responsivities (R_peak) of 35 mA/W at -4 V and show an abnormal increase of the response (R_peak > 100 A/W) under forward biases. [reprint (PDF)]
18.	Wafer-scale epitaxial lift-off of optoelectronic grade GaN from a GaN substrate using a sacrificial ZnO interlayer Akhil Rajan, David J Rogers, Cuong Ton-That, Liangchen Zhu, Matthew R Phillips, Suresh Sundaram, Simon Gautier, Tarik Moudakir, Youssef El-Gmili, Abdallah Ougazzaden, Vinod E Sandana, Ferechteh H Teherani, Philippe Bove, Kevin A Prior, Zakaria Djebbour, Ryan McClintock and Manijeh Razeghi Journal of Physics D: Applied Physics, Volume 49, Number 31 -- July 15, 2016 ...[Visit Journal] Full 2 inch GaN epilayers were lifted off GaN and c-sapphire substrates by preferential chemical dissolution of sacrificial ZnO underlayers. Modification of the standard epitaxial lift-off (ELO) process by supporting the wax host with a glass substrate proved key in enabling full wafer scale-up. Scanning electron microscopy and x-ray diffraction confirmed that intact epitaxial GaN had been transferred to the glass host. Depth-resolved cathodoluminescence (CL) analysis of the bottom surface of the lifted-off GaN layer revealed strong near-band-edge (3.33 eV) emission indicating a superior optical quality for the GaN which was lifted off the GaN substrate. This modified ELO approach demonstrates that previous theories proposing that wax host curling was necessary to keep the ELO etch channel open do not apply to the GaN/ZnO system. The unprecedented full wafer transfer of epitaxial GaN to an alternative support by ELO offers the perspective of accelerating industrial adoption of the expensive GaN substrate through cost-reducing recycling. [reprint (PDF)]
18.	The correlation between x-ray diffraction patterns and strain distribution inside GaInP/GaAs superlattices X.G. He, M. Erdtmann, R. Williams, S. Kim, and M. Razeghi Applied Physics Letters 65 (22)-- November 28, 1994 ...[Visit Journal] Strong correlation between x‐ray diffraction characteristics and strain distribution inside GaInP/GaAs superlattices has been reported. It is found that the symmetry of (002) diffraction patterns can be used to evaluate the interface strain status. A sample with no interfacial strains has a symmetric (002) diffraction pattern and weak (004) diffraction pattern. It is also demonstrated that strain distribution in superlattices can be readily estimated qualitatively by analyzing x-ray diffraction patterns. [reprint (PDF)]
18.	Band gap tunability of Type-II Antimonide-based superlattices M. Razeghi and B.M. Nguyen Physics Procedia, Vol. 3, Issue 2, p. 1207-1212 (14th International Conference on Narrow Gap Semiconductors and Systems NGSS-14, Sendai, Japan, July 13-17, 2009)-- January 31, 2010 ...[Visit Journal] Current state-of-the art infrared photon detectors based on bulk semiconductors such as InSb or HgCdTe are now relatively mature and have almost attained the theoretical limit of performance. It means, however, that the technology can not be expected to demonstrate revolutionary improvements, in terms of device performances. In contrasts, low dimensional quantum systems such as superlattices, quantum wells, quantum dots, are still the development stage, yet have shown comparable performance to the bulk detector family. Especially for the Type-II Antimony-based superlattices, recent years have seen significant improvements in material quality, structural design as well as fabrication techniques which lift the performance of Type-II superlattice photodetectors to a new level. In this talk, we will discuss the advantages of Type-II-superlattices, from the physical nature of the material to the practical realisms. We will demonstrate the flexibility in controlling the energy gap and their overall band alignment for the suppression of Auger recombination, as well as to create sophisticated hetero-designs. [reprint (PDF)]
18.	Very high performance LWIR and VLWIR type-II InAs/GaSb superlattice photodiodes with M-structure barrier B.M. Nguyen, D. Hoffman, P.Y. Delaunay, E.K. Huang and M. Razeghi SPIE Proceedings, Vol. 7082, San Diego, CA 2008, p. 708205-- September 3, 2008 ...[Visit Journal] LWIR and VLWIR type-II InAs/GaSb superlattice photodetectors have for long time suffered from a high dark current level and a low dynamic resistance which hampers the its emergence to the infrared detection and imaging industry. However, with the use of M-structure superlattice, a new Type-II binary InAs/GaSb/AlSb superlattice design, as an effective blocking barrier, the dark current in type-II superlattice diode has been significantly reduced. We have obtained comparable differential resistance product to the MCT technology at the cut-off wavelength of 10 and 14μm. Also, this new design is compatible with the optical optimization scheme, leading to high quantum efficiency, high special detectivity devices for photon detectors and focal plane arrays. [reprint (PDF)]
18.	The first fabrication of n- and p-type Ga0.49In0.51P/Ga(In)As lattice matched and strained HIGFET structures grown by MOCVD M Razeghi, F Omnes, M Defour, P Maurel, P Bove, Y J Chan and D Pavlidis M Razeghi et al 1990 Semicond. Sci. Technol. 5 274-- December 11, 1989 ...[Visit Journal] The authors report the first fabrication of Ga0.49In0.51P/GaxIn1-xAs n- and p-type lattice matched (x=1) and strained (x-0.85) heterostructure insulated gate field effect transistor (HIGFET) grown by low-pressure metal-organic chemical vapour deposition (LP MOCVD). The growth conditions of Ga0.49In0.51P have been optimised to produce a high-purity insulator material. The n-type devices show good pinch-off characteristics, with a small variation of threshold voltage with temperature consecutive to the low trap density in that system. High transconductance values have been obtained on p-type devices, due to the large valence band discontinuity between GaAs and Ga0.49In0.51P. [reprint (PDF)]
18.	Very low threshold buried ridge structure lasers emitting at 1.3 μm grown by low pressure metalorganic chemical vapor deposition M. Razeghi; R. Blondeau; K. Kazmierski; M. Krakowski; J. P. Duchemin Appl. Phys. Lett. 46 (2): 131–133.-- January 15, 1985 ...[Visit Journal] GaInAsP‐InP buried ridge structure lasers emitting at 1.3 μm have been fabricated on material grown completely by low pressure metalorganic chemical vapor deposition. These lasers have low threshold (11 mA), exhibit linear (kink‐free) light‐current characteristics up to high powers (10 mW/facets), and can be operated at high temperatures (70 °C). Excellent uniformity over 10 cm2 has been obtained, and an external quantum efficiency of 60% for two faces has been measured. [reprint (PDF)]
18.	Scaling in back-illuminated GaN avalanche photodiodes K. Minder, J.L. Pau, R. McClintock, P. Kung, C. Bayram, M. Razeghi and D. Silversmith Applied Physics Letters, Vol. 91, No. 7, p. 073513-1-- August 13, 2007 ...[Visit Journal] Avalanche p-i-n photodiodes of various mesa areas were fabricated on AlN templates for back illumination for enhanced performance through hole-initiated multiplication, and the effects of increased area on device performance were studied. Avalanche multiplication was observed in mesa sizes up to 14,063 µm^2 under linear mode operation. Uniform gain and a linear increase of the dark current with area were demonstrated. [reprint (PDF)]
18.	Current status and potential of high power mid-infrared intersubband lasers S. Slivken, Y. Bai, B. Gokden, S.R. Darvish and M. Razeghi SPIE Proceedings, San Francisco, CA (January 22-28, 2010), Vol. 7608, p. 76080B-1-- January 22, 2010 ...[Visit Journal] Some of the recent advances in high power quantum cascade laser development will be reviewed in this paper. Research areas explored include short wavelength (λ <4 µm) lasers, high performance strain-balanced heterostructures, and high power long wavelength (7< λ< 16 µm) lasers. Near λ=4.5 µm, highlights include demonstration of 18% continuous wave wallplug efficiency at room temperature, 53% pulsed wallplug efficiency at 40 K, and 120 W of peak power output from a single device at room temperature. Near λ ~10 µm, up to 0.6 W of continuous output power at room temperature has also been demonstrated, with pulsed efficiencies up to 9%. [reprint (PDF)]
18.	New frontiers in InP based quantum devices Manijeh Razeghi Indium Phosphide and Related Materials, 2008. IPRM 2008. 20th International Conference on, pp.1,4, (2008)-- May 29, 2008 ...[Visit Journal] Recent research activities taking place at center for quantum devices (CQD) based on InP material system, especially the exploration and demonstration of the state-of-art high performance quantum cascade lasers (QCL), greatly facilitate the understanding of the underlining physical principles governing the device operation. Thanks to the endless effort putting into the semiconductor epitaxy technologies, including the Molecular Beam Epitaxy (MBE) and low pressure metal organic chemical vapor deposition (LP-MOCVD), the world has seen a close approaching to the ultimate band gap engineering. Highly sophisticated man-made heterostructure, which incorporates hundreds of alternating layers of GaInAs/AlInAs with each layer thickness and composition specifically designed, can be created within a single growth. The material quality is evidenced by the atomically abrupt interfaces. The versatility of the band gap engineering is greatly enhanced by the strain-balanced technique, which allows for growing structures with continuously tunable conduction band offset with little defects. As a result, the room temperature continuous wave (CW) wall plug efficiency (WPE) and the maximum achievable output optical power from a single device have been constantly improving. Novel waveguide incorporating the photonic crystal distributed feedback (PCDFB) mechanism is also investigated with satisfactory preliminary results. [reprint (PDF)]
18.	Aluminum free GaInP/GaAs Quantum Well Infrared Photodetectors for Long Wavelength Detection C. Jelen, S. Slivken, J. Hoff, M. Razeghi, and G. Brown Applied Physics Letters 70 (3)-- January 20, 1997 ...[Visit Journal] We demonstrate quantum well infrared photodetectors based on a GaAs/Ga_0.51In_0.49P superlattice structure grown by gas-source molecular beam epitaxy. Wafers were grown with varying well widths. Wells of 40, 65, and 75 Å resulted in peak detection wavelengths of 10.4, 12.8, and 13.3 μm with a cutoff wavelength of 13.5, 15, and 15.5 μm, respectively. The measured peak and cutoff wavelengths match those predicted by eight band theoretical analysis. Measured dark currents were lower than equivalent GaAs/AlGaAs samples. [reprint (PDF)]
18.	Imprinting of Nanoporosity in Lithium-Doped Nickel Oxide through the use of Sacrificial Zinc Oxide Nanotemplates Vinod E. Sandana, David J. Rogers, Ferechteh H. Teheran1, Philippe Bove, Ryan McClintock and Manijeh Razeghi Proc. SPIE 10105, Oxide-based Materials and Devices VIII, 101052C-- April 3, 2017 ...[Visit Journal] Methods for simultaneously increasing the conductivity and the porosity of NiO layers grown by pulsed laser deposition (PLD) were investigated in order to develop improved photocathodes for p-DSSC applications. NiO:Li (20at%) layers grown on c-Al₂O₃ by PLD showed a sharp drop in conductivity with increasing substrate temperature. Layers grown at room temperature were more than two orders of magnitude more conductive than undoped NiO layers but did not show evidence of any porosity in Scanning Electron Microscope (SEM) images. A new method for imposing a nanoporosity in NiO was developed based on a sacrificial template of nanostructured ZnO. SEM images and EDX spectroscopy showed that a nanoporous morphology had been imprinted in the NiO overlayer after preferential chemical etching away of the nanostructured ZnO underlayer. Beyond p-DSSC applications, this new process could represent a new paradigm for imprinting porosity in a whole range of materials. [reprint (PDF)]
18.	Room temperature terahertz quantum cascade laser sources with 215 μW output power through epilayer-down mounting Q. Y. Lu, N. Bandyopadhyay, S. Slivken, Y. Bai, and M. Razeghi Appl. Phys. Lett. 103, 011101 (2013)-- July 1, 2013 ...[Visit Journal] We report room temperature terahertz (THz) quantum cascade laser sources with high power based on difference frequency generation. The device is Čerenkov phase matched and spectrally purified with an integrated dual-period distributed-feedback grating. Symmetric current injection and epilayer-down mounting of the device onto a patterned submount are used to improve the electrical uniformity and heat removal, respectively. The epilayer-down mounting also allows for THz anti-reflective coating to enhance the THz outcoupling efficiency. Single mode emission at 3.5 THz with a side-mode suppression ratio and output power up to 30 dB and 215 μW are obtained, respectively. [reprint (PDF)]
18.	Non-equilibrium radiation of long wavelength InAs/GaSb superlattice photodiodes D. Hoffman, A. Hood, F. Fuchs and M. Razeghi Journal of Applied Physics 99-- February 15, 2006 ...[Visit Journal] The emission behavior of binary-binary type-II InAs/GaSb superlattice photodiodes has been studied in the spectral range between 8 and 13 μm. With a radiometric calibration of the experimental setup the internal and external quantum efficiencies have been determined in the temperature range between 80 and 300 K for both the negative and positive luminescences. [reprint (PDF)]
18.	Noise analysis in Type-II InAs/GaSb Focal Plane Arrays P.Y. Delaunay and M. Razeghi Virtual Journal of Nanoscale Science and Technology, Vol. 20, No. 14-- October 5, 2009 ...[Visit Journal][reprint (PDF)]
18.	EPR Investigations of a Structural Phase Change in Lead Phosphate M. RAZEG M. RAZEGHI: EPR Investigations of a Structural Phase Change, phys. stat. sol. (b) 108, 175 (1981)-- April 10, 2010 ...[Visit Journal] The temperature dependence of the EPR line width of the Mn2+ and Gd3+ in Pb,(PO,), is investigated from -270 to 500 "C. At the first-order ferroelastic transition point (180 "C), an abrupt change in the fine-structure splitting as well as in the resonance line width is observed. Various contributions to fine structure D and E parameters of Mn2+ and Gd3+ are computed, using a point-multipole model. For temperatures near to Tc the correlation time of the fluctuations is estimated to be greater than Die Temperaturabhangigkeit der EPR-Linienbreite von Mn2+,'und Gd3+ in Pb,(PO,), wird zwischen -270 und 500 "C untersucht. Am ferroelastischen vbergangspunkt erster Ordnung (180 "C) wird eine abrupte Anderung der Feinstrukturaufspaltung sowie der Linienbreite der Resonanzlinien beobachtet. Verschiedene Beitrage zu den Feinstrukturparametern D und E von Mn2+ und Gd3+ werden mittels eines Punkt-Multipol-Modells berechnet. Fur Temperaturen in der Nahe von T, wird die Korrelationszeit der Fluktuationen eu groI3er als s. s bestimmt. [reprint (PDF)]
18.	Solar-blind photodetectors based on Ga₂O₃ and III-nitrides Ryan McClintock; Alexandre Jaud; Lakshay Gautam; Manijeh Razeghi Proc. SPIE 11288, Quantum Sensing and Nano Electronics and Photonics XVII, 1128803-- January 31, 2020 ...[Visit Journal] Recently, there has been a surge of interest in the wide bandgap semiconductors for solar blind photo detectors (SBPD). This work presents our recent progress in the growth/doping of AlGaN and Ga₂O₃ thin films for solar blind detection applications. Both of these thin films grown are grown by metal organic chemical vapor deposition (MOCVD) in the same Aixtron MOCVD system. Solar-blind metal-semiconductor-metal photodetectors were fabricated with Ga₂O₃. Spectral responsivity studies of the MSM photodetectors revealed a peak at 261 nm and a maximum EQE of 41.7% for a −2.5 V bias. We have also demonstrated AlGaN based solar-blind avalanche photodiodes with a gain in excess of 57,000 at ~100 volts of reverse bias. This gain can be attributed to avalanche multiplication of the photogenerated carriers within the device. Both of these devices show the potential of wide bandgap semiconductors for solar blind photo detectors. [reprint (PDF)]
18.	Persistent photoconductivity in thin undoped GaInP/GaAs quantum wells S. Elhamri, M. Ahoujja, K. Ravindran, D.B. Mast, R.S. Newrock, W.C. Mitchel, G.J. Brown, I. Lo, M. Razeghi and X. He Applied Physics Letters 66 (2)-- January 9, 1995 ...[Visit Journal] Persistent photoconductivity has been observed at low temperatures in thin, unintentionally doped GaInP/GaAs/GaInP quantum wells. The two‐dimensional electron gas was studied by low field Hall and Shubnikov–de Haas effects. After illumination with red light, the electron concentration increased from low 10¹¹ cm⁻² to more than 7×10¹¹ cm⁻² resulting in an enhancement of both the carrier mobility and the quantum lifetime. The persistent photocarriers cannot be produced by DX-like defects since the shallow dopant concentration in the GaInP layers is too low to produce the observed concentration. We suggest that the persistent carriers are produced by photoionization of deep intrinsic donors in the GaInP barrier layer. We also report observation of a parallel conduction path in GaInP induced by extended illumination. [reprint (PDF)]
18.	Positive and negative luminescence in binary Type-II InAs/GaSb superlattice photodiodes D. Hoffman and M. Razeghi SPIE Conference, San Jose, CA, Vol. 6127, pp. 61271H-- January 23, 2006 ...[Visit Journal] In the present work, we show measurements of both positive and negative luminescence of binary Type-II InAs/GaSb superlattice photodiodes in the 3 to 13 μm spectral range. Through a radiometric calibration technique, we demonstrate temperature independent negative luminescence efficiencies of 45 % in the midwavelength (MWIR) sample from 220 K to 320 K without anti-reflective coating and values reaching 35 % in the long wavelength infrared (LWIR) spectrum sample. [reprint (PDF)]
18.	Widely tuned room temperature terahertz quantum cascade laser sources Q.Y. Lu, N. Bandyopadhyay, S. Slivken, Y. Bai and M. Razeghi SPIE Proceedings, Vol. 8631, p. 863108-1, Photonics West, San Francisco, CA-- February 3, 2013 ...[Visit Journal] Room temperature THz quantum cascade laser sources with a broad spectral coverage based on intracavity difference frequency generation are demonstrated. Two mid-infrared active cores in the longer mid-IR wavelength range (9-11 micron)based on the single-phonon resonance scheme are designed with a second-order difference frequency nonlinearity specially optimized for the high operating fields that correspond to the highest mid-infrared output powers. A Čerenkov phase-matching scheme along with integrated dual-period distributed feedback gratings are used for efficient THz extraction and spectral purification. Single mode emissions from 1.0 to 4.6 THz with a side-mode suppression ratio and output power up to 40 dB and 32 μW are obtained, respectively. [reprint (PDF)]
18.	Multiple-band, Single-mode, High-power, Phase-locked, Mid-infrared Quantum Cascade Laser Arrays Manijeh Razeghi, Wenjia Zhou, Quanyong Lu, Donghai Wu, and Steven Slivken Imaging and Applied Optics 2018, JTh1A.2-- September 15, 2018 ...[Visit Journal] Single-mode, 16-channel, phase-locked laser arrays based on quantum cascade laser technology are demonstrated at multiple spectral bands across the mid-infrared spectrum region. High peak output power of 50W is achieved around the long-wavelength band of 7.7µm, while a side mode suppression ratio over 25dB is obtained. Far field distribution measurement result indicates a uniform phase distribution across the array output. [reprint (PDF)]
18.	Highly selective two-color mid-wave and long-wave infrared detector hybrid based on Type-II superlattices E.K. Huang, M.A. Hoang, G. Chen, S.R. Darvish, A. Haddadi, and M. Razeghi Optics Letters, Vol. 37, No. 22, p. 4744-4746-- November 15, 2012 ...[Visit Journal] We report a two-color mid-wave infrared (MWIR) and long-wave infrared (LWIR) co-located detector with 3 μm active region thickness per channel that is highly selective and can perform under high operating temperatures for the MWIR band. Under back-side illumination, a temperature evolution study of the MWIR detector’s electro-optical performance found the 300 K background-limit with 2π field-of-view to be achieved below operating temperatures of 160 K, at which the temperature’s 50% cutoff wavelength was 5.2 μm. The measured current reached the system limit of 0.1 pA at 110 K for 30 μm pixel-sized diodes. At 77 K, where the LWIR channel operated with a 50% cutoff wavelength at 11.2 μm, an LWIR selectivity of ∼17% was achieved in the MWIR wave band between 3 and 4.7 μm, making the detector highly selective. [reprint (PDF)]
18.	p-Type thin film field effect transistors based on lithium-doped nickel oxide channels grown by pulsed laser deposition V. E. Sandana; D. J. Rogers; F. H. Teherani; P. Bove; R. McClintock; M. Razeghi SPIE Proceedings Volume 10919, Oxide-based Materials and Devices X; 109191H -- March 12, 2019 ...[Visit Journal] Staggered back-gated Field Effect Transistor (FET) structures were made by growing Li-doped NiO on Si₃N₄/SiO₂/Si (111) using room temperature pulsed laser deposition. Optical studies showed over 80% transmission for the NiO:Li channel at wavelengths > 500nm. The MISFET revealed rectifying transfer characteristics, with a V_ON close to zero, a channel mobility of ~ 1 cm²/V·s, a gate leakage current (at +5V) of 0.8 mA and an ION/IOFF ratio (at a Vgs of −15V) of ~ 10³. The transistors showed enhancement-mode output characteristics indicative of a p-type channel with sharp pinchoff, hard saturation, a comparatively high (milliampere range) Id and a relatively low on-resistance of ~11 kΩ. Hence the adoption of Li doping in NiO channels would appear to be a promising approach to obtain p-type TFTs with superior transparency, speed and energy efficiency. [reprint (PDF)]
18.	Temperature dependence of threshold current density J_th and differential efficiency of High Power InGaAsP/GaAs ( λ = 0.8 μm) lasers H. Yi, J. Diaz, I. Eliashevich, M. Stanton, M. Erdtmann, X. He, L. Wang, and M. Razeghi Applied Physics Letters 66 (3)-- January 16, 1995 ...[Visit Journal] An experimental and theoretical study on temperature dependence of the threshold current density J_th and differential efficiency ηd for the InGaAsP/GaAs laser diodes emitting at λ=0.8 μm was performed. Threshold current density J_th increases and differential efficiency η_d decreases as temperature is increased mainly because of thermal broadening of the gain spectrum. However, the measured temperature dependence of J_th and η_d could not be explained when only this effect was considered. In this letter, the temperature dependence of momentum relaxation rate ℏ/τ of carriers was investigated by performing the photoluminescence study. At high temperature, increase of the momentum relaxation rate ℏ/τ leads to reduction of the gain and mobility and increase of the optical loss, causing higher J_th and lower η_d as experimentally observed. The resulting theoretical model provides a good explanation for the mechanism of the increase of J_th and decrease of η_d. [reprint (PDF)]
18.	Scale-up of the Chemical Lift-off of (In)GaN-based p-i-n Junctions from Sapphire Substrates Using Sacrificial ZnO Template Layers D. J. Rogers, S. Sundaram, Y. El Gmili, F. Hosseini Teherani, P. Bove, V. Sandana, P. L. Voss, A. Ougazzaden, A. Rajan, K.A. Prior, R. McClintock, & M. Razeghi Proc. SPIE 9364, Oxide-based Materials and Devices VI, 936424 -- March 24, 2015 ...[Visit Journal] (In)GaN p-i-n structures were grown by MOVPE on both GaN- and ZnO-coated c-sapphire substrates. XRD studies of the as-grown layers revealed that a strongly c-axis oriented wurtzite crystal structure was obtained on both templates and that there was a slight compressive strain in the ZnO underlayer which increased after GaN overgrowth. The InGaN peak position gave an estimate of 13.6at% for the indium content in the active layer. SEM and AFM revealed that the top surface morphologies were similar for both substrates, with an RMS roughness (5 μm x 5 μm) of about 10 nm. Granularity appeared slightly coarser (40nm for the device grown on ZnO vs 30nm for the device grown on the GaN template) however. CL revealed a weaker GaN near band edge UV emission peak and a stronger broad defect-related visible emission band for the structure grown on the GaN template. Only a strong ZnO NBE UV emission was observed for the sample grown on the ZnO template. Quarter-wafer chemical lift-off (CLO) of the InGaN-based p-i-n structures from the sapphire substrate was achieved by temporary-bonding the GaN surface to rigid glass support with wax and then selectively dissolving the ZnO in 0.1M HCl. XRD studies revealed that the epitaxial nature and strong preferential c-axis orientation of the layers had been maintained after lift-off. This demonstration of CLO scale-up, without compromising the crystallographic integrity of the (In)GaN p-i-n structure opens up the perspective of transferring GaN based devices off of sapphire substrates industrially. [reprint (PDF)]

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