Spectroscopic study of partially ordered semiconductor heterojunction under high pressure and high magnetic field

Photoluminescence upconversion (PLU) is a phenomenon in which a sample emit s photons with energy higher than that of the excitation photon. This effec t has been observed in many materials, including rare earth ions doped in i nsulating hosts and semiconductor heterostructures without using high-power lasers as the excitation source. Recently this effect has been observed al so in partially CuPt-ordered GaInP2 epilayers grown on GaAs substrates. As a spectroscopic technique, PLU is particularly well suited for studying ban d alignment at heterojunction interfaces. The value of band offset has been determined with meV precision using magneto-photoluminescence. Using the f act that the pressure coefficient of electrons in GaAs is higher than that in GaInP2 we have been able to 'manipulate' the band offset at the GaInP/Ga As interface. By converting the band offset from type I to type II we were able to demonstrate that the efficiency of the upconversion process is grea tly enhanced by a type II band offset. Copyright (C) 2001 John Wiley & Sons , Ltd.