Sn delta-doping in GaAs

TL;DR

This study demonstrates that Sn delta-doping in GaAs via molecular beam epitaxy achieves higher electron densities than other dopants, with detailed magnetotransport analysis confirming multiple subband populations and agreement with bandstructure calculations.

Contribution

It introduces Sn as an effective delta-dopant in GaAs, providing detailed experimental and theoretical analysis of resulting electronic properties.

Findings

Maximum carrier density of 8.4x10^13 cm^-2 achieved

Multiple subbands populated at high doping levels

Good agreement between experiments and bandstructure calculations

Abstract

We have prepared a number of GaAs structures delta-doped by Sn using the well-known molecular beam epitaxy growth technique. The samples obtained for a wide range of Sn doping densities were characterised by magnetotransport experiments at low temperatures and in high magnetic fields up to 38 T. Hall-effect and Shubnikov-de Haas measurements show that the electron densities reached are higher than for other delta-dopants, like Si and Be. The maximum carrier density determined by the Hall effect equals 8.4x10^13 cm^-2. For all samples several Shubnikov-de Haas frequencies were observed, indicating the population of multiple subbands. The depopulation fields of the subbands were determined by measuring the magnetoresistance with the magnetic field in the plane of the delta-layer. The experimental results are in good agreement with selfconsistent bandstructure calculations. These calculation shows that in the sample with the highest electron density also the conduction band at the L point is populated.