Browse Prior Art Database

Ohmic Contacts to P-Type Semiconductors

IP.com Disclosure Number: IPCOM000048260D
Original Publication Date: 1982-Jan-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Chang, LL: AUTHOR [+2]

Abstract

The use of p-GaSb provides ohmic contacts to p-type semiconductors. The essence of this technique lies in utilizing the unique property of GaSb, i.e., at its interface with a metal, the fermi level is pinned close to energy, resulting in an accumulation of holes. Transport of carriers across the interface, consequently, shows an ohmic behavior. To provide ohmic contacts to other p-type semiconductors requires a transition layer where the compositions are graded to GaSb from whatever semiconductors are of interest. The drawing shows the configuration for making ohmic contact to p-type GaAs, for example. The graded layer in this case is made of GaSb(1-x) As(x) , with x varying from 0 to 1 at the GaAs interface. To contrast the situation, the configuration of making ohmic contacts to n-GaAs with n-InAs is also shown.

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Ohmic Contacts to P-Type Semiconductors

The use of p-GaSb provides ohmic contacts to p-type semiconductors. The essence of this technique lies in utilizing the unique property of GaSb, i.e., at its interface with a metal, the fermi level is pinned close to energy, resulting in an accumulation of holes. Transport of carriers across the interface, consequently, shows an ohmic behavior. To provide ohmic contacts to other p-type semiconductors requires a transition layer where the compositions are graded to GaSb from whatever semiconductors are of interest. The drawing shows the configuration for making ohmic contact to p-type GaAs, for example. The graded layer in this case is made of GaSb(1-x) As(x) , with x varying from 0 to 1 at the GaAs interface. To contrast the situation, the configuration of making ohmic contacts to n-GaAs with n-InAs is also shown.

The depositions of both the GaSb and the graded layer, GaSb(1-x)As(x), can be done with conventional processes. The technique of molecular beam epitaxy offers special advantages in terms of its capability of thickness and compositional control. It also ensures a continuous alloy range of GaSb(1-x)As(x) where a miscibility gap around x approximately equal 0.5 was sometimes reported by other techniques.

The configuration shown in the drawing for GaAs can obviously be applied to other semiconductors, such as GaP, AlAs or even InP, which do not share a common element with GaSb, as long as a proper graded layer is used...