24 March 2015 Scale-up of the chemical lift-off of (In)GaN-based p-i-n junctions from sapphire substrates using sacrificial ZnO template layers
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Proceedings Volume 9364, Oxide-based Materials and Devices VI; 936424 (2015) https://doi.org/10.1117/12.2175897
Event: SPIE OPTO, 2015, San Francisco, California, United States
Abstract
(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.
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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, "Scale-up of the chemical lift-off of (In)GaN-based p-i-n junctions from sapphire substrates using sacrificial ZnO template layers", Proc. SPIE 9364, Oxide-based Materials and Devices VI, 936424 (24 March 2015); doi: 10.1117/12.2175897; https://doi.org/10.1117/12.2175897
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