Controlled low barrier height n⁺-InGaAs/n-GaAs pseudomorphic heterojunction schottky diodes

Heterojunction Schottky barrier diodes, in which a pseudomorphic layer of n+-InGaAs played the role of a metal contacting n-GaAs, were grown by molecular beam epitaxy. The junctions had low barrier heights (30-150 meV) which could be controlled by composition and doping of the n+ layer. I-V measurements of the devices confirmed that the devices behaved as Schottky diodes, in accordance with the theory of tunneling and thermally assisted tunneling in the temperature range 4-200 K. An exponential increase in conductance with decreasing In concentration indicates a decrease in barrier height which is at least qualitatively consistent with simulations of the barriers based on earlier experiments, which showed that the band-gap discontinuity appears predominately in the conduction band.