Molecular beam epitaxy of InAlN∕GaN heterostructures for high electron mobility transistors

We describe the growth of InAlN∕GaN heterostructures by rf-plasma molecular beam epitaxy. Due to the weak In–N bond, the InAlN growth temperature must be below about 460°C for In to incorporate reliably into the film. Thus far, a thin AlN spacer layer has been required to form a low resistance two dimensional electron gas (2DEG) at the InAlN∕GaN interface. The thin AlN barrier is believed to reduce alloy scattering of carriers in the 2DEG. The best HEMT material with an InAlN barrier and a thin AlN spacer layer has a sheet resistance of 980Ω∕◻ with a sheet electron density of 1.96×1013cm−2.