High current gain GaN bipolar junction transistors with regrown emitters

We present the high current gain operation of n-p-n GaN bipolar junction transistors using regrown emitters. Devices were grown by metalorganic chemical vapor deposition on sapphire substrates. The n-type emitter was grown selectively on a base-collector p-n junction diode using a dielectric mask. A thin base (800 Å) was used to increase the current gain over our previous result with a regrown emitter [J.B. Limb, H. Xing, B. Moran, L. McCarthy, S.P. DenBaars, and U.K. Mishra, Appl. Phys. Lett. 76, 17(2000)]. Common emitter operation showing a collector voltage operation of over 70 V with a current gain of ~8, has been demonstrated at room temperature. The current gain of ~8 is corresponding to a current transfer ratio of ~0 89. This results in a calculated minority carrier lifetime of about 100 ps in the base