Ohmic contact to p-type GaAs using Cu3Ge

Abstract

We have investigated ε1−Cu3Ge as an ohmic contact to p-type GaAs, and found that the ε1−Cu3Ge contact has a specific contact resistivity of 5×10−6 Ω cm2 on p-type GaAs with doping concentrations of ∼7×1018 cm−3. The ε1−Cu3Ge contact exhibits a planar and structurally abrupt interface with the GaAs, and no reaction between the contact metal and the GaAs is required for contact formation. The contact is electrically stable during annealing at temperatures up to 400 °C. It is suggested that Ge is incorporated into the GaAs as a p-type impurity resulting in a low contact resistivity. Furthermore, the addition of Ge to Cu to form ε1−Cu3Ge is found to impede the diffusion of Cu into the p-type GaAs. Along with the results reported for n-type GaAs, the present results indicate that ε1−Cu3Ge is an attractive candidate for ohmic contact formation on both n- and p-type GaAs.

Physical Analysis of a Possibility to Reach the 1.30-μm Emission from the GaAs-Based VCSELs with the InGaAs/GaAs Quantum-Well Active Regions and the Intentionally Detuned Optical Cavities

“…Typical values of their contact resistances are equal to 10 −5 cm 2 (n-side) and 10 −4 cm 2 (p-side) (reported values, see e.g. Aboelfotoh et al (1999) and Ueng et al (2001), are even much lower).…”

Thermal stability, mechanical and electrical properties of nanocrystalline Cu3Ge

“…This compound was shown to have a reduced resistivity comparable to high purity copper when small amounts of Ga or Au are added. It has further been shown that Cu 3 Ge can make low resistance p and n type ohmic contacts to GaAs substrates which are more thermally stable than the current contact metallurgies [27,28]. These properties make the 3 1 compound Cu 3 Ge an ideal material for the next generation of electronic materials used for high power applications.…”

Selective chemical vapor synthesis of Cu3Ge: Process optimization and film properties

“…6a and d) shows Cu 3 Ge layers exhibited sharp and planar interfaces with the underlying surfaces [3,7,17]. Such sharp interfaces of the films may be crucial for contact formation and shallow junction devices [9,14,15,35]. In addition, this low temperature process avoids the morphological instability and new interface phase formation which are otherwise noticed in the PVD-techniques after thermal annealing [6,22,34].…”