THE HOLE TRANSPORT CHARACTERISTICS IN SIGE/SI DOUBLE AND TRIPLE BARRIER RESONANT TUNNELING STRUCTURES

Experimental measurements and theoretical calculations have been used to study the hole transport characteristics in SiGe/Si double and triple barrier resonant tunneling structures. The main emphasis is put on discussing the symmetry of I-V characteristics with forward and reverse bias, their temperature dependences and relations to quantum well designs. The calculations show that at current resonance, the sub-level can be much lower (e.g, for heavy hole resonance) or much higher (e.g, for light hole resonance) than the quasi-Fermi-level in the spacer. The distinctly different features of the measured first and second resonances for SiGe/Si double and triple barrier resonant tunneling, can be understood, by considering the different population of the heavy hole and light hole bands in the spacer region and the temperature dependences of Fermi-level, carrier mobility and effective masses. The analysis of dependences of the transmission and I-V curve with quantum well designs presents the possibility of using an asymmetric triple barrier structure to improve the resonant tunneling performance. © 1992.