Low-temperature grown MnAs/InAs/MnAs double heterostructure on GaAs (111)B by molecular beam epitaxy

Abstract

We used MBE to grow a double heterostructure of MnAs/InAs/MnAs on GaAs(111)B at low temperature for vertical spin FET applications. To confirm the ideal development environment, we primarily prepared single InAs thick layer (∼1.2 μm) at low growth temperature (∼250 °C) with varied V/III ratio (As/In = 2, 10, 20) due to the challenge of growing InAs at much lower temperature than its usual growth temperature (∼480 °C). We measured their structural and electrical properties and found an optimum condition at V/III ratio of 10. Afterwards, we prepared the double heterostructure at low temperature (∼250 °C), again varying the As/In beam equivalent pressure ratio to find its influence on the overall quality of the structure. Using atomic force microscopy, we observed the surface roughness variation corresponding to V/III ratio variation of InAs. We confirmed the growth of three individual thick layers of MnAs and InAs by cross-sectional analysis using scanning electron microscopy and energy-dispersive X-ray spectroscopy. Using a superconducting quantum interference device magnetometer, we found in-plane easy magnetization and observed the effect of top and bottom MnAs layers on the hysteresis curve. We also found the existence of ferromagnetic behavior of MnAs layers at RT MH measurements. The MnAs/InAs/MnAs double heterostructure on GaAs(111)B, in our opinion, has potential as a structure for spin FETs.