AN EXTREMELY LOW OFFSET VOLTAGE ALINAS GAINAS HETEROSTRUCTURE-EMITTERBIPOLAR-TRANSISTOR/

A new Al0.48In0.52As/Ga0.47In0.53As heterostructure-emitter bipolar tr ansistor (HEBT) with a very low offset voltage of 40 mV has been fabri cated by molecular beam epitaxy. From the theoretical analysis and exp erimental results, it is found that a 500-Angstrom thick emitter used in the studied device can effectively eliminate the potential spike at the N-AlInAs/n-GaInAs heterointerface. However, a degenerate current gain of about 25 is obtained, attributed to the increase of recombinat ion current at the neutral-emitter regime. This is caused by the short hole diffusion length of GaInAs, which reduces the emitter injection efficiency. Due to the small surface recombination velocity, the emitt er edge-thinning design is not essential to improve the device perform ance of our proposed AlInAs/GaInAs HEBT. (C) 1998 Academic Press Limit ed.