Electrical properties and deep levels of InAlAs layers grown by metalorganic chemical vapor deposition

Abstract

Deep donors whose thermal activation energy is about 250 meV are detected in undoped InAlAs layers grown by MOCVD. These deep donors determine the background carrier concentrations and cause a discrepancy between the donor concentrations measured by capacitance-voltage measurements and free carrier concentrations measured by Hall measurements. Oxygen as high as 1019 cm-3 is detected in these InAlAs layers. Oxygen atoms are thought to be the probable candidates of the deep donors. Oxygen in InAlAs layers is also thought to form deep levels, whose activation energies are 0.5 eV (level A), 0.3 eV (level B), 0.07 eV (level C), and 0.45 eV (level D). The reduction of oxygen in InAlAs layers results in low concentrations of both deep donors and deep levels.