Characterization of resonant tunneling diodes
Necessary steps for integrating a RTD (Resonant Tunneling Diode) into circuit networks is presented. This work is motivated by the fact that RTD is essentially a low-powered device whose power output can be improved only a little by using different material systems and different geometries. Therefore, to obtain high output power, integration of oscillators is necessary. In order to design a system which incorporates the device, bias network and matching network, it is essential to have an accurate equivalent circuit model for the device. A design methodology using computer simulation to obtain equivalent circuit parameters by using material and geometry parameters is presented. An integration compatible, microwave probe station compatible device structure is designed and tested. As with non-integrated devices, the series resistance represents a significant limitation to device performance. Since the contact resistances dominate the overall series resistance, the specific resistances must be minimized. However, the double barrier RTD structure under study can not be characterized using usual TLM measurement; an equivalent circuit model has been proposed and analytical solutions of voltage, current and total resistance in terms of geometry parameters and material parameters are presented which in turn can be used to determine the specific contact resistance information from the measured data. A new top contact material system, namely, LTG (Low Temperature Grown) GaAs, is evaluated. This material system can reduce the contact resistance in order to boost the performance of RTDs fabricated using the new integration compatible structure.
Janes, Purdue University.
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