Optoelectronics and Optical Fiber Sensors by Asit Baran Maity

Author:Asit Baran Maity [Maity, Asit Baran]
Language: ell
Format: azw3
Published: 2013-06-12T04:00:00+00:00

Chapter 6

Photodetectors

6.1 INTRODUCTION

The photodetector plays an important role in all information processing units and finds wide applicability even in various domestic electronic and optoelectronic systems [1– 6]. This device detects or absorbs optical signal and converts it into electrical signal.

In ideal case, a detector made by intrinsic materials usually detects optical signal whose energy is very close to its fundamental bandgap (ho ≥ Eg). On absorbing the incident photon, the ground state (valance band) electrons become excited and take a transition to higher energy state (conduction band), as shown in Fig. 6.1 and contribute in external photocurrent of the device. An efficient process of photodetection involves three important steps which are as follows:

(a) Absorption of optical energy and generation of photogenerated electron-hole pair.

(b) Quick transportation of the photogenerated carriers across the absorption region, before recombination.

(c) Carrier collection and generation of photocurrent at the terminal side of the device.

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