Ohmic contact to p-GaN using a strained InGaN contact layer and its thermal stability

We have formed ohmic contacts to p-GaN using a strained p-InGaN contact layer, and achieved the lowest contact resistance of 1.1 x 10(-6) Omega-cm(2) at room temperature by optimizing the contact layer thickness and its In mole-fraction. We have also evaluated thermal stability of ohmic contacts to p-GaN using. the strained p-InGaN contact layer. The contact resistance decreased to 2 x 10(-7) Omega-cm(2) at 100degreesC, and increased with elevating temperature above 100degreesC. In the temperature range up to 400degreesC, the contact resistances of the samples with the p-InGaN contact layer were smaller than those of the samples without the contact layer. Furthennore, the ohmic characteristics of the strained p-InGaN contact layer were less degraded even after the thermal process, compared with those of the sample without a content layer. These results indicate that the strained p-InGaN contact layer is favorable for practical application.