A hybrid epitaxy method for InAs on GaP

Abstract

The interface formation mechanism during the molecular-beam epitaxy (MBE) of InAs∕GaP has been studied with the aid of the In–Ga–P phase diagram. It is discovered that an initial dissolution and crystallization process similar to liquid phase epitaxy (LPE) may happen at sufficiently high temperature, resulting in a graded composition at the interface. Consequently, “parasitic LPE∕MBE” is the name for this hybrid form of MBE. High-resolution TEM images confirm the existence of the interfacial layer in the sample grown at high temperature. The graded interface smears out the band offset and leads to a nonrectifying heterojunction. Low-temperature (LT) MBE growth can turn off the LPE component, enabling the growth of an abrupt interface. Based on this “LPE∕MBE” model, a LT MBE technique is developed to grow an abrupt InAs∕InGaP interface for heterojunction power Schottky rectifiers. The LT InAs∕InGaP heterojunction demonstrates nearly ideal Schottky rectifier characteristics, while the sample grown at high temperature shows resistive ohmic characteristics. The LT InAs∕InGaP Schottky diode also demonstrates good stability with respect to anneal temperature, similar to the InAs∕GaP heterojunctions.