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Improved 1.3 Micron Light Detector Using Fermi Level Engineering

IP.com Disclosure Number: IPCOM000105019D
Original Publication Date: 1993-Jun-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Hodgson, RT: AUTHOR [+3]

Abstract

A semiconductor such as GaAs can be loaded with metallic or semimetal particles, which can then eject electrons when illuminated with photons of energy less than the semiconductor bandgap energy. This material can then be used as a detector of such submicron light by building the structure sketched in Fig. 1a. An n type GaAs substrate 1 has a first layer 2 of n type GaAs, a second layer 3 of undoped GaAs: As grown at low temperature (200C), and a third layer 4 of p type GaAs grown on it. Metal electrodes 5 collect current between electrodes 5 and substrate 1 when sub band gap light 6 impinges on and ejects carriers from the metallic arsenic inclusions in layer 3. The potential vs depth of such a structure is shown in Fig.

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Improved 1.3 Micron Light Detector Using Fermi Level Engineering

      A semiconductor such as GaAs can be loaded with metallic or
semimetal particles, which can then eject electrons when illuminated
with photons of energy less than the semiconductor bandgap energy.
This material can then be used as a detector of such submicron light
by building the structure sketched in Fig. 1a.  An n type GaAs
substrate 1 has a first layer 2 of n type GaAs, a second layer 3 of
undoped GaAs:  As grown at low temperature (200C), and a third layer
4 of p type GaAs grown on it.  Metal electrodes 5 collect current
between electrodes 5 and substrate 1 when sub band gap light 6
impinges on and ejects carriers from the metallic arsenic inclusions
in layer 3.  The potential vs depth of such a structure is shown in
Fig. 1b, where curve 7 is the valence band energy, curve 8 is the
fermi energy, and curve 9 is is the conduction band energy.

      A problem with the device as disclosed is that the internal
fields in the intrinsic material containing the particles is shorted
out, and the voltage is dropped over a short distance next to the
doped regions of the device as sketched in Fig. 1b.

      If we grade the material composition of the layer 3 so the
composition varies from 'GaAs:As'  to 'Ga' sub 0.9 'Al' sub 0.1
'As:As' and replace layer 4 with p type
 'Ga' sub 0.9  'Al' sub 0.1 'As' , the potential vs depth of the
device will be as sketched in Fig. 2, and the internal fields...