Sub-threshold velocity-field characteristics of InAs1-xPx alloys

Abstract

The velocity‐field characteristics of n‐type InAs1‐xPx alloys are determined up to the threshold electric field for current instabilities by pulsed current‐voltage measurements on undoped epitaxial layers grown on semi‐insulating InP substrates. For x > 0.3 the current instabilities are caused by avalanche multiplication, while for x > 0.3 they are produced by transferred electron effects. By equating the threshold energies for these two mechanisms at x = 0.3, the γL intervalley separation is estimated at 0.71 eV for InAs0.7P0.3. Adding arsenic to InP reduces the threshold electric field from 8.5 kV cm−1 in InP to 2.75 kV cm−1 in InAs0.7P0.3 without significantly altering the peak velocity which remained constant at ≈ 2.4 × 107 cm s−1. This variation of threshold field and peak velocity in the transferred electron regime is in reasonable agreement with recent theoretical predictions.