Reduction of operation voltage in GaN-based light-emitting diode utilizing a Si δ-doped n-GaN contact layer

We have investigated the characteristics of InGaN/GaN blue light-emittg diodes (LEDs) with a Si delta (δ)-doped GaN contact layer. The Si δ-doping could enhance the Si doping concentration and improve the lateral conductivity in the GaN:Si contact layer without cracking. The operation voltage and dynamic resistance of LEDs with a Si δ-doped GaN contact layer were 3.65 Ω and 27.0 Ω at 20 mA, respectively. Meanwhile, the operation voltage and dynamic resistance of conventional LEDs with a uniformly doped GaN:Si contact layer were 3.94 V and 32.3 Ω at 20 mA, respectively. The operation voltage reduction might be related to the high Si concentration and improvement of crystalline quality due to the Si δ-doping into the contact layer. In addition, the light emission efficiency was improved by the Si δ-doping in the n-GaN contact layer.