HEAVILY DOPED GAAS(BE)/GAALAS HBTS GROWN BY MBE WITH HIGH DEVICE PERFORMANCES AND HIGH THERMAL-STABILITY

In this study, the increase of the 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 allowed to obtain a very high value (70) for the maximum current gain with a base sheet resistance of 145-OMEGA/square, for heavily doped base HBT devices processed with a conventional low-temperature double-mesa technology. We have also demonstrated the first operational heavily doped base HBT devices processed with an implanted high-temperature technology, exhibiting a dc current gain as high as 30.