ACTA

Study of Two-Dimensional Hole Gas at Si/SiGe/Si Inverted Interface

M.A. Sadeghzadeh^a, O.A. Mironov^a, C.J. Emeleus^b, C.P. Parry^a, P.J. Phillips^a, E.H.C. Parker^a and T.E. Whall^a
^aDepartment of Physics, University of Warwick, Coventry, CV4 7AL, U.K.
^bDepartment of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, U.K.

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We have studied the transport properties of a two-dimensional hole gas (2DHG) at the inverted interface of a strained Si_0.8Ge_0.2 quantum well. By application of a bias voltage to a Schottky gate on top of this inverted heterostructure the 2DHG density n_s can be controlled, in the range of (1.5-5.2)×10¹¹ cm^-2. At a temperature T=0.33 K, the Hall mobility is 4650 cm² V^-1 s^-1 at the maximum carrier density. For lower sheet densities (n_s<2×10¹¹ cm^-2) the system undergoes a transition from a weak to strongly localised phase of significantly reduced mobility. From low temperature Shubnikov-de Haas oscillation measurements we have extracted the hole effective masses m*=(0.25 → 0.28)m₀ and the ratio of transport to quantum lifetimes α=(0.92 → 0.85) for the corresponding carrier density change of n_s=(5.2 → 2.5)×10¹¹ cm^-2. These results can be explained in terms of the abnormal movement of the hole wave function towards the interface with decreasing n_s, short range interface charge and interface roughness scattering.

DOI: 10.12693/APhysPolA.94.503
PACS numbers: 73.20.Fz