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Three dimensional numerical modeling and simulation of a uniformly doped GaAs MESFET photodetector

K. BALASUBADRA1, T.THANGAM2, V. RAJAMANI3,* , K. SANKARANARAYANAN4

Affiliation

  1. K.L.N.College of Information Techn., Sivagangai, TN, India - 630 611
  2. PSNA College of Engineering and Technology, Dindigul, Tamilnadu, India – 624 622
  3. Indra Ganesan College of Engineering, Manikandam, Tiruchirappalli, TN, India - 620 012
  4. V.L.B. Janakiammal Engg. College, Coimbatore, TN, India - 641 042

Abstract

A new 3D numerical model of a GaAs MESFET Photo detector has been presented in this paper. The model takes into account all the major effects that determine the device characteristics in the illuminated condition. It has been found that in a short channel MESFET photo detector, the drain current saturation is caused by the velocity saturation of the carriers rather than the pinch off condition. By considering both the photo conductive effect in the channel and photo voltaic effect at the gate schottky barrier, the major limitations of the existing model have been overcome. A three dimensional Poisson’s equation has been solved with suitable boundary conditions to obtain the potential profile in the channel. The electric field profile along the length, width and thickness of the channel and mobility of the carriers have also been studied extensively under illuminated condition. Calculations are being carried out to examine the effect of illumination on the current-voltage characteristics, internal gate-to-source capacitance (Cgs ), drain to source capacitance(Cds ), drain to source resistance (Rds) and tranconductance(gm) Due to effect of photo generation in the semi insulating substrate, the device characteristics are strongly influenced. The results of numerical calculations show that there is an increase in electron mobility and switching speed under the illumination condition. The proposed model is fairly accurate and can be used for accurate simulation of OptoElectronic Integrated Circuits (OEIC) using uniformly doped GaAs MESFET photo detector..

Keywords

Device simulation, numerical 3D modeling, GaAs MESFET, Photo detector, OEIC.

Submitted at: Jan. 1, 2008
Accepted at: Oct. 7, 2008

Citation

K. BALASUBADRA, T.THANGAM, V. RAJAMANI, K. SANKARANARAYANAN, Three dimensional numerical modeling and simulation of a uniformly doped GaAs MESFET photodetector, Journal of Optoelectronics and Advanced Materials Vol. 10, Iss. 10, pp. 2494-2501 (2008)