The effect of Mg diffusion on the contact resistance of low doped p-GaN

Summary form only given. Although the rapid progress on this material system already makes the commercial laser diodes (LDs) available, still, the critical issue for the device is the lifetime. One of the factors affecting the lifetime is the high p-type contact resistance of the devices, which generates ohmic heating preventing the devices from cw or long-life operation. The obstacles of making a low resistance p-type contact to GaN are mainly in the difficulty to obtain a high in-situ doping level in p-GaN, and the lack of a metal with a large work function to eliminate or reduce the band offset. In this letter we report for the first time that Mg diffusion was applied to low doped GaN (/spl sim/3 /spl times/ 10/sup 16/ cm/sup -3/) using Mg/sub 3/N/sub 2/ as Mg source to reduce the resistance of contact to p-GaN. The results have consistently showed a reduction of contact resistance by /spl sim/1.5 orders of magnitude.