FREQUENCY RESPONSE CHARACTERIZATION OF GaAs MSM PHOTODETECTOR ARRAYS: TEST FACILITY AND EXPERIMENTAL RESULTS
Date
1995-05
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Degree Level
Masters
Abstract
Frequency domain measurements of responsivity and modulation bandwidth were made for GaAs metal-semiconductor-metal (MSM) photodetector arrays. Photodetector arrays, in which several photodetectors drive a common signal bus, have applications as optical to electrical converters in optoelectronic switching and signal processing elements. The MSM detector is an attractive
candidate for these applications due to its ease of fabrication and integration, its low dark current and noise, and its speed.
Measurements for three detector sizes and two array sizes consistently showed that MSM detectors exhibit a position dependent response as part of an array. If the array is terminated in a load at one end of the common signal bus only, the bandwidth of the detectors increases with distance from the load. Terminating the bus at both ends reduces the position dependence of the response and significantly increases the half-power bandwidth of all detectors in the array.
A test facility was designed and constructed to allow frequency testing of high speed photodetectors at 830 nm up to 18 GHz using a vector network analyzer. A temperature stabilized continuous wave laser light source is modulated using an electro-optic Y-fed balanced bridge modulator (YBBM) and the modulated light illuminates the test photodetectors. The system is calibrated using a commercially available, wideband InGaAs Schottky photodiode with known response.
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Degree
Master of Science (M.Sc.)
Department
Electrical Engineering