Patent ID: 9653631
Date: 2017-05-16
CPC Classifications: H01L

Claim:
1. A heterostructure comprising: an active region; a p-type contact layer having a p-type contact layer dopant concentration; an electron blocking layer located between the active region and the p-type contact layer, wherein a p-type dopant concentration in the electron blocking layer is at most ten percent of the p-type contact layer dopant concentration, and wherein an aluminum content in the electron blocking layer is higher than an aluminum content in the p-type contact layer; and a p-type interlayer located between the electron blocking layer and the p-type contact layer, wherein a dopant concentration in the p-type interlayer increases from a dopant concentration comparable to the p-type dopant concentration in the electron blocking layer to a dopant concentration comparable to the p-type contact layer dopant concentration in a direction from the electron blocking layer to the p-type contact layer, and wherein the p-type interlayer includes a plurality of sublayers that form a superlattice including a first group of high aluminum content sublayers alternating with a second group of low aluminum content sublayers, each sublayer having a semiconductor alloy composition that differs from a semiconductor alloy composition of an immediately adjacent sublayer by at least 0.5%, and wherein an aluminum content in the second group of low aluminum content sublayers decreases from a first side adjacent to the electron blocking layer to a second side adjacent to the p-type contact layer.