Document Type
Thesis
Date of Award
6-30-1991
Degree Name
Master of Science in Electrical Engineering - (M.S.)
Department
Electrical and Computer Engineering
First Advisor
Ken K. Chin
Second Advisor
Walter F. Kosonocky
Third Advisor
Marek Sosnowski
Abstract
The simulation of signal coupling for a single pixel of a monolithic 8-12 micron GaAs/A1GaAs direct injection MQW infrared image sensor with 100% fill factor has been performed by using PISCES-IIB and PSPICE simulators. A vertical structure with the readout circuit built on the back of MQW was adopted for simulations. Both the static and transient characteristics were analyzed by simulation. The simulation was used to verify the doping profiles and device parameters for the n-GaAs MESFETs used in the read-out circuit.
The simulation result is as follow:
(1) A 900A thick p-GaAs (p=1016/cm3) substrate for GaAs MESFETs is used to avoid the direct leakage of the signal from MQW to the read-out circuit through the substrate of MESFET. The vertical pixel structure is suitable for direct injection MQW focal plane array(FPA). An optional n-substrate for MESFETs was considered, but the leakage is noticeable.
(2) With a 300K background photocurrent of the MQW photodetector as small as 10-10Amps, the GaAs MESFET leakage current must be less than 10-12Amps. Our simulation shows that with V7-=-0.5Volts, both the gate leakage current and the source-to-drain leakage current are less than 10-13Amps.
(3) A storage capacitor of 1.0pF is required for a signal of 10-1?Amp in order to match the video frame frequency(16ms/frame). If the signal is 10-9Amps, a larger capacitor of 10.0pF has to be used. In both cases the time of optical integration can be as high as 16ms.
(4) The minimum charge transfer time for single pixel is l0ns; for a 512x512 FPA the minimum charge transfer time is 2.6ms. This satisfies the requirement of the application.
Recommended Citation
Zhang, Lei, "Simulation study of signal coupling for monolithic GaAs 8-12 micron direct injection MQW image sensor" (1991). Theses. 2685.
https://digitalcommons.njit.edu/theses/2685
