Two kinds of monolithically fabricated circuits are demonstrated in GaAs-based material systems using resonant tunneling diodes（RTD） and metal-semiconductor-metal photo detectors（MSM PD）. The electronic characteristics of these fabricated RTD devices,MSM devices,and integrated circuits are tested at room temperature. The results show that the current peak-to-valley ratio is 4,and the photocurrent at 5V is enhanced by a factor of nearly 9,from 2 to about 18μA by use of recessed electrodes. The working theory and logical functions of the circuits are validated.
Resonant tunneling diode （RTD） of AlAs/InGaAs/AlAs double barrier-single well structure was designed and fabricated. The devices showed current-voltage characteristics with peak-valley current ratio of 4 ： 1 at room temperature. The scattering parameter of RTD was measured by using an HP8510（C） network analyzer. Equivalent circuit parameters were obtained by curve fitting and optimized. The RTD switching time was estimated using the measured capacitance and average negative differential resistance. The minimum rise time of the sample was estimated to be 21 ps.
A novel optoelectronic functional circuit with heterojunction phototransistors (HPTs) and resonant tunneling diodes (RTDs) is described,which presents the function of both photocurrent switching and photo-current latching.These behaviors have been demonstrated by simulating experiments and circuit simulation.Furthermore,basing on photo-current latching behavior,various photo-controlled basis logic elements such as delayed flip-flop (DFF) can be designed and fabricated.
The distinction between two microwave equivalent-circuit models,quasi Esaki tunneling model (QETM) and quantum well injection transit model (QWITM),for the resonant tunneling diode (RTD) is discussed in details,and two groups of circuit parameters are extracted from experiment data by the least square fit method.Both theory analysis and the comparison of fit results demonstrate that QWITM is much more precise than QETM.In addition,the rationality of QWITM circuit's parameters confirms it too.On this basis,the resistive frequency is calculated,whose influence factors and improvement method are simply discussed as well.
