Doping and electrical properties of Mn in In1−x−yGaxAlyAs grown by molecular beam epitaxy

Abstract

Epitaxial layers of p-type In1−x−yGaxAlyAs doped with Mn were grown by molecular beam epitaxy. The doping characteristics and electrical properties are studied using Hall measurements in the temperature range between 100 and 300 K. Secondary ion mass spectrometry (SIMS) was used to study Mn profiles and diffusion coefficients. The maximum hole concentration attainable at room temperature is relatively independent of the As flux and is found to decrease from 4×1018 for y=0 to 2×1016 cm−3 for y=0.48. The experimental results of the resistivity and Hall effect are used to determine the densities Na, Nd of acceptors and compensating donors and the activation energy. The acceptor activation energy Ea increases from 50 at y=0 to 200 meV at y=0.23. Ea is found to be independent of the hole concentration and the arsenic flux used during the molecular beam epitaxial growth. The hole mobility for hole concentration of ∼1017 cm−3 is about 140 cm2 V−1 s−1 and decreases with increasing y. SIMS measurements of the Mn profiles show that Mn diffusion is significant at temperatures 650 °C and above, but is insignificant under the growth condition at 493 °C. Abrupt junction and sharp Mn pulses (<0.15 μm wide) have been obtained. Mn surface segregation is negligible at growth temperatures above 500 °C.