Properties of Schottky barriers and p-n junctions prepared with GaAs and Alx Ga1−x As molecular beam epitaxial layers

Abstract

The properties of molecular beam epitaxy (MBE) that are relevant to device applications have been investigated. Precise control of layer thickness is one of the most attractive features of MBE, and layers from a few hundred angstroms to 10 μ may readily be grown. Unintentionally doped GaAs layers grown on 〈100〉-oriented substrates are n type, and room-temperature carrier concentrations of ∼2 × 1015 cm−3 with a mobility of ∼6000 cm2/V sec have been obtained. Schottky barriers on MBE n-type GaAs layers demonstrate that defect-free devices with uniform properties may be prepared at the present time. Junctions of p- and n-type MBE have also been fabricated and have been found to compare favorably with p-n junctions prepared by other techniques. Heterojunctions of GaAs and Alx Ga1−xAs have also been prepared and evaluated. The p-type Alx Ga1−xAs layers are suitable for heterostructure applications, while n-type Alx Ga1−xAs layers tend to be high resistivity at the present time.