Enhancement of photocurrent in InGaN/pseudo-AlIGaN multi quantum wells by surface acoustic wave

In this work, we have investigated the variation of internal electric field of 4-period In_0.16Ga_0.84N/pseudo-AlInGaN multiquantum wells (MQWs) embedded in p-i-n structure by surface acoustic waves (SAWs). The pseudo-AlInGaN barriers consist of two In_0.16Ga_0.84N(11 Å) sandwiched by three Al_0.064Ga_0.936N (15 Å). The equivalent indium and aluminum compositions in pseudo-AlInGaN barrier are 0.043 and 0.052, respectively, which can be calculated by volume ratio. For reference purpose, In_0.16Ga_0.84N/GaN MQWs was also used. To generate surface acoustic wave, interdigital patterns with 1 μm finger width were fabricated by e-beam lithography. The piezoelectric fields for GaN barrier and pseudo- Al_0.043In_0.052Ga_0.905N barrier samples are found to be 1.5 MV/cm, 0.33 MV/cm from bias-PL. From μ-PL measurement for pseudo-Al_0.043In_0.052Ga_0.905N barrier sample, we observed lowest luminescence intensity at 100 MHz and 13 dBm in radio frequency (RF) generator, which means that electron-hole recombination can be suppressed by SAWs. The Photocurrent measurement for pseudo-Al_0.043In_0.052Ga_0.905N barrier sample was observed increasing around 2 orders of magnitude at 100 MHz when compare to GaN barrier sample. Based on our results, the reduced piezoelectric field added to SAWs can be provided one of the solutions for enhancing photocurrent in III-nitride photovoltaic devices by extract carriers from quantum wells easily and enhancing traveling length of carriers.