APPLİCATİON OF İONİZATİON TYPE INFRARED IMAGE CONVERTER SYSTEMS FOR STUDY OF PHYSICAL PROPERTIES OF PHOTODETECTOR


Thesis Type: Postgraduate

Institution Of The Thesis: Gazi University, Fen Bilimleri Enstitüsü, Turkey

Approval Date: 2010

Thesis Language: Turkish

Student: Sadık ÇETİN

Supervisor: HATİCE HİLAL KURT

Abstract:

Infrared (IR) photodetector instabilities of IR image converter was studied experimentally in a wide range of the gas pressures (p= 28-342 Torr), interelectrode distances (d1 = 50 μm d2 = 50 – 320 μm) and different diameters (D= 12-15 mm) of the photodetector areas. The current voltage characteristics (CVC) of the double gas discharge system with GaAs semiconductor was studied. While being driven with a stationary voltage, it generates current instabilities with different amplitudes of oscillation. It was unambiguously proved that instabilities in the IR image converter may be provoked by a photodetector, depending on the experimental conditions. N-shape instabilities of CVC was determined. The presence of deep electronic levels of defects, so called EL2 centers, give rise to the N-type NDR of the material, as a consequence, to oscillations in current when a dc voltage of a high enough magnitude is applied to a GaAs photodetector. Due to the gas discharge dualrange, Current-Voltage and Current-Time charts modulation was observed. In addition, for large distance between electrodes, hysteresis curves were obtained.