OPTICAL AND ELECTRICAL INVESTIGATION OF AN ASYMMETRIC STRAINED-LAYER DOUBLE-BARRIER RESONANT-TUNNELING STRUCTURE

An optical and electrical investigation of an asymmetric GaAs-AlGaAs-b ased double-barrier resonant-tunnelling structure containing a straine d-layer In(y)Ga1-yAs (y = 0.11) quantum well region is reported. Photo luminescence (PL) and PL excitation (PLE) spectroscopies are employed to determine the variation of charge (n(s)) build-up in the quantum we ll as a function of applied bias. Very large values of n(s), as high a s 1 x 10(12) cm-2, due to the thick collector barrier width of 130 ang strom employed, are deduced. The charge density results of the optical experiments are then used in Poisson equation simulations of the devi ce. The results are found to account very well for the observed curren t-voltage characteristics of the structure. In particular the occurren ce of inverted bistability, where the off-resonance current is greater than the on-resonance current over the whole range of the bistable re gion, is found to be consistent with the results of the device simulat ions.