Evidence of n-type Doping in Cubic Boron Arsenide

Cubic boron arsenide (BAs) is a recently emerging semiconductor that has exceedingly high thermal conductivity. However, the lack of charge carrier concentration control in cubic BAs is a significant hindrance to its application in electronic devices. As-grown micro crystals of BAs are reported to be unintentionally p-type. Here, the evidence of inhomogeneous n-type behavior in BAs crystals grown by an improved growth process reducing the impurities is present. Local n-type doping is confirmed by four methods: current-voltage measurement, scanning photocurrent microscopy, Kelvin Probe Force Microscopy, and Hall effect. Their analysis enables the formulation of a model describing BAs band bending on contacts and bias. Analysis of scanning photocurrent microscopy reveals that the diffusion length of minority carriers in BAs is substantial, reaching 33 µm. Defect analysis performed by current transient spectroscopy, photo-induced current transient spectroscopy and X-ray photoelectron spectroscopy shows that silicon-substituted boron is a candidate for a donor in BAs. Presented results show the perspective for bipolar control of charge carrier type in BAs and consequently its application in better thermally managed microelectronics.