AC RESPONSE OF BIPOLAR DOUBLE-BARRIER RESONANT-TUNNELING STRUCTURES

We have developed an explicit formulation of the total intrinsic admit tance of bipolar double-barrier resonant-tunneling structures. The the ory includes contributions from the tunneling currents through the bar riers and the recombination current, as well as from the charge distri bution. We have numerically solved the problem for small ac voltage am plitudes in the framework of linear response. The calculations are ful ly quantum mechanical in the Hartree approximation. In linear response , and at frequencies below the internal frequency of the system, the s usceptance is found to be entirely of a capacitive nature. We have stu died both an ordinary bipolar double-barrier resonant-tunneling struct ure and an optimized resonant-tunneling light emitting diode. We have investigated the frequency dependence of the admittance as well as the dependence on recombination time. In both samples a delta-shaped peak in the susceptance is found in the negative differential resistance r egion. However, the details of the frequency response are found to be closely related to the specific structure under consideration. [S0163- 1829(98)04739-0].