Ballistic Electron Emission Microscopy and Spectroscopy Study of Ordering-Induced Band Structure Effects in Ga0.52In0.48P

Abstract

Ordering induced changes in the band structure of GaInP are important with regard to its device applications, as well as for fundamental studies of atomic ordering. To characterize the structural and electronic properties of Ga0.52In0.48P (written as GaInP2 for simplicity), we have used the Ballistic Electron Emission Microscopy (BEEM) technique which allows the study of buried heterostructures with high spatial resolution. To make the most out of the BEEM capabilities, this work has detailed a quantitative study of the second voltage derivative (SD) of the ballistic electron emission spectra. Then, we associate two peaks observed in the SD-BEEM spectra of disordered GaInP2 on n+ GaAs substrate with the F and L conduction minima, whereas an additional third peak in the SD-BEEM spectra of ordered GaInP2 we associate with the L-band splitting due to the ordering-induced “folding” of one (from four) L valley onto the \( \bar \Gamma \) point. According to our results, this splitting is 0.13meV for the ordered GaInP2 (η∼0.5). In addition, the BEEM images of ordered GaInP2 samples show regions of enhanced and reduced current on the scale of ∼0.5 μm, and we relate these BEEM contrast regions to be due to order parameter fluctuations or antiphase domain boundaries.