Patent ID: 7485946

Claim:
A transistor epitaxial wafer, comprising: a substrate; an n-type collector layer, a p-type base layer, and an n-type emitter layer formed on the substrate in this order; and an n-type InGaAs non-alloy layer comprising an n-type InGaAs nonuniform composition layer formed on the n-type emitter layer and comprising an nonuniform indium (In) composition, and an n-type InGaAs uniform composition layer formed on the n-type InGaAs nonuniform composition layer and comprising a uniform indium (In) composition, wherein the n-type InGaAs nonuniform composition layer comprises a first layer doped with Si and comprising a low indium (In) composition, and a second layer formed on the first layer, doped with an n-type dopant except Si, and comprising an indium (In) composition higher than the first layer.