WELL WIDTH DEPENDENCE OF TUNNELING CURRENT IN DOUBLE-QUANTUM-WELL RESONANT INTERBAND TUNNEL-DIODES

Current-voltage characteristics of double-quantum-well (DQW) resonant interband tunnel (RIT) heterojunction InGaAlAs diodes with well widths of 20, 30, 40, and 60 angstrom are experimentally investigated at room temperature and compared. Peak current density exhibits a maximum at the 40-angstrom well width, which is an order of magnitude greater than the peak current densities of other well widths. The calculation of the positions of electronic states leads to the following simple explanation: there are no bound states in the 20- and 30-angstrom wells. In the 40-angstrom well, one electronic state appears near the top of the well. This state, which coincides with the Fermi level, is responsible for resonant transmission. In the 60-angstrom well, the only electronic state is too deep and too far from the Fermi level for resonance to occur.