Title of Submission
Ge2Se3/Ge2Se3-M (M = Sn, Al, Ti, W, Cr, Pb, Cu, C)-Based Optically-Gated Transistor: M Influence on Optical and Electrical Properties
Electrical and Computer Engineering, PhD
Major Advisor Name
Type of Submission
Electronic devices made with alternating layers of undoped and doped chalcogenide materials, Ge2Se3/Ge2Se3-M (M = Sn, Al, Ti, W, Cr, Pb, Cu, C) exhibit transistor-like current-voltage (I-V) curves when illuminated. These devices referred to as optically-gated transistors (OGTs), have two electrodes: a source and drain. Current is measured between the source and drain electrodes when the chalcogenide material (which acts as a ‘gate’) is illuminated. In this work, the effect of the metal dopant on the transistor characteristics are measured. The transistor materials are characterized using UV-Vis to explore the band gap and electronic structure. Raman spectroscopy is used to verify incorporation of M into the Ge2Se3 material. Photoconduction is investigated using electrical characterization as a function of wavelength, light intensity, and temperature. The devices were tested from 385 to 1200 nm and were operational over that entire range.
The metal dopant is shown to clearly influence the transistor optical responsivity, maximum current, threshold voltage, electrical switching speed, and optical band gap. A transistor fabricated with M = Al is demonstrated in three applications: as an access transistor to a memristor memory element for cross point array element isolation; as an optical amplifier; and in an optical wavelength converter circuit.