Robust p-type behavior in polycrystalline, ball-milled, magnesium-doped Bi2Se3

We study polycrystalline pellets of magnesium doped Bi2Se3 compacted from powders processed with planetary milling, a high energy crude metallurgical method. We present evidence that the specimens are p-type and that hole conduction is robust over a wide temperature range. The p-type behavior was probed at room temperature and above with Hall and Seebeck coefficient measurements. The first order non-parabolicity approximation was used to show that holes contribute a higher thermoelectric power compared to that of electrons in agreement with recent theoretical band structure calculations.