Graded-base InGaN∕GaN heterojunction bipolar light-emitting transistors

The authors report radiative recombination from a graded-base InGaN∕GaN heterojunction bipolar transistor (HBT) grown by metal-organic chemical vapor deposition on sapphire. For a device with a 40×40μm2 emitter area, a differential dc current gain of 15 is measured from the common-emitter current-voltage characteristics, with the HBT breakdown voltage BVCEO>65V. The heterojunction bipolar light-emitting transistor exhibits a base-region recombination radiation peak in the visible spectral range with a dominant peak at λ=385nm (blue emission).