(Ga,In)P emitter composition effect on the performance of (Ga,In)P/GaAsSb/InP DHBTs grown by MOCVD



(Ga,In)P/GaAsSb DHBTs with different emitter sizes were fabricated with the standard triple-mesa process on wafers with GaInP [Ga] emitter contents of 0, 0.15, 0.24 in the emitter. The effect of the gallium content on the DC and RF characteristics of the DHBTs was studied. It was found that gain increases as the Ga mole fraction increases. This is due to a reduced surface recombination current and intrinsic recombination current with increasing [Ga]. 0.45 × 9.5 μm2 devices with a Ga content of 0.24 show the highest cut-off frequency of 387 GHz. This is attributed to the reducing barrier at the E/B interface, which eases the injection of electrons from the emitter into the GaAsSb base. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)