n-ZnO:Ga/i-ZnO/p-Si heterojunction light emitting diodes fabricated on patterned Si substrates

n -ZnO:Ga/ i -ZnO/ p -Si heterojunction light-emitting diodes were fabricated on patterned Si substrates with increased interface area where hole carriers were transported to the i -ZnO layer. The patterned Si substrates were prepared by electrochemical etching, and the n -type ZnO:Ga films were deposited by high-temperature sputtering. In the patterned LED, the lower breakdown and greater leakage current under a reverse bias was attributed to the formation of a high density of grain boundaries and random tilting of the c -axis. Compared to an LED without patterning, the patterned substrates resulted in approximately 75% improvement in the output power of visible emission, which was attributed to a 1.33-fold increase in the heterojunction area and the increase in grain boundary density due to grain tilting.