Relationship between the conduction-band discontinuities and band-gap differences of InGaAsP/InP heterojunctions

Abstract

We have measured the magnitude of the conduction‐band discontinuities at heterojunctions for several compositions of InGaAsP grown lattice matched on InP. We find that the conduction‐band discontinuity (ΔE_c) is related to the difference in band gaps (ΔE_g) between the InGaAsP and InP layers via ΔE_c =0.39(ΔE_g). Thus, 40% of the band‐gap difference lies in the conduction band of this material system. The measurements were made on a series of composition of InGaAsP spanning the alloy range from In_0.53Ga_0.47As (with energy gap E_g =0.75 eV) to InP (E_g =1.35 eV) using capacitance‐voltage techniques. Depletion deep into the semiconductor layers was facilitated by the formation of organic‐on‐inorganic semiconductor contact barriers on the InGaAsP surface.