Investigation of p-contact performance for indium rich InGaN based light emitting diodes and solar cells

Abstract

We report on the optimization of p-GaN layers for high indium (In) content InGaN applications by optimizing temperature, precursor CP 2 Mg flow rate and III/V ratio and report also on the optimization of p-contact performance. Using MOVPE, a 150 nm thick p-type GaN with moderate Mg doping and a 50 nm contact layer with high Mg doping concentration were grown on standard GaN templates at growth temperatures in the range of 850-1000 8C. Hall measurement yields hole concentration of 4.8 Â 10 17 cm À3 for the optimized sample. SIMS shows Mg concentration of 1.7 Â 10 20 cm À3 on average in the heavily doped and 4 Â 10 19 cm À3 on average in the moderately doped p-GaN layer for the optimized p-GaN. A multilayer Pd/Ag/Ni/Au metal contact has been deposited on this p-GaN and studied using the CTLM technique. Optimization of both p-GaN layers and p-contact processing led to a low resistance contact with specific contact resistivity of 6 Â 10 À4 Ω cm 2 . We believe, the very high Mg concentration of the surface layer in intimate contact with the contact metal reduces the Schottky barrier height and band bending. This optimization of p-GaN is an important step towards high efficiency green LEDs and solar cells.

New Architecture of ZnGeN2/In0.16Ga0.84N Type‐II Quantum Well‐Based Green Emitting LED

“…To overcome this problem, a possible way lies in the development of new QW structures such as staggered InGaN QW, [6] strain-compensated InGaN/AlGaN QW, [7] or InGaN/InGaN QW. [8] Another way to reach a green-emitting LED would be to consider a new architecture by inserting a new semiconductor, ZnGeN 2 , [9] inside a standard InGaN well.…”