Characterization of MOVPE-grown p-InGaAs/n-InP interfaces

The low-pressure MOVPE-grown p-InGaAs-on-n-InP and n-InP-on-p-InGaAs diodes were characterized by I–V and C–V measurements to study the effects of the growth conditions on the heterointerface. The obtained band discontinuity in the conduction band ΔE_c ranged from 0.19 to 0.32 eV. It was found that ΔE_c was very sensitive to the growth interruption at the InP/InGaAs heterointerface. The n-InP-on-p-InGaAs diodes tend to show higher ΔE_c than the p-InGaAs-on-n-InP diodes. The decreased ΔE_c at InGaAs-on-InP heterointerface might be attributed to the graded layer of InGaAsP formed by intermixing at the interface. It is concluded from the estimated ΔE_c that the InP-on-InGaAs heterointerface is more abrupt than the InGaAs-on-InP heterointerface. An improvement of the InGaAs-on-InP heterointerface is mandatory for fabrication of high-performance double heterojunction bipolar transistors with InP collector layers.