Heavily doped GaAs(Be)/GaAlAs HBTs grown by MBE with high device performances and high thermal stability

In this study, the increase of V/III flux ratio combined with a low growth temperature has been found to lead to a drastic improvement of the HBT current gain, and also to avoid the base dopant (Be) diffusion during high post-growth process annealing. The optimized growth conditions have made it possible to obtain a very high value (70) for the maximum current gain with a base sheet resistance of 145 Omega / Square Operator , for heavily doped base HBT devices processed with a conventional low-temperature double-mesa technology. The authors have also demonstrated operational heavily doped HBT devices processed with an implanted high-temperature technology and exhibiting a DC current gain as high as 30.<
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