SiGe heterostructure field-effect transistor using V-shaped confining potential well

A working p-type SiGe heterostructure field-effect transistor, utilizing a Vshaped confining potential well as the conducting channel, has been successfully fabricated. The upper boron (delta)-doping layer acts as a diffusion barrier to slow diffusion into the undoped Si cap layer. On the other hand, the bottom boron (delta)-doping layer prevents hot holes from escaping the channel by improving carrier confinement. It is found that when a V-shaped confining potential well is used as the conducting channel, the devices exhibit the excellent property not only of higher current density but also enhancement in extrinsic transconductance and linear operation range over a wider dynamic range than those of (delta)-doped devices for the same dose in SiGe conducting well. The measured transconductance is enhanced three to six times over that of the other (delta) cases.