Description
Holes in silicon are a promising approach to quantum devices due to their strong intrinsic spin-orbit coupling and compatibility with legacy semiconductor fabrication. However, recent work by Wendoloski et al. [1] suggests that holes in silicon have a larger transverse effective mass than naïve expectations, approximately $0.6m_0-0.7m_0$, as compared with the traditional band-edge value of $m^*=0.22m_0$. For hole-spin quantum dots, an increased effective mass reduces the energy scales and level spacing by approximately $E\sim (m^*)^{-\frac{1}{2}}$, and increases the susceptibility to disorder. This makes fabrication and operation of hole-based quantum devices more challenging than their electron counterparts. Hence a reduction in effective mass would directly improve device performance and scalability. Theoretical studies by Donetti et al. [2] suggests that MOSFETs made on (110) interfaces could display up to half the effective mass of conventional (100) silicon.
We systematically investigate the properties of 2D holes in silicon MOSFETs with crystallographic orientations (100), (110), and (111), using Si/SiOx Hall bar devices. We present measurements of hole transport at low temperatures (down to T=1.6K) to isolate orientation-dependent effects from phonon scattering, and along multiple in-plane directions to account for direction-dependent effects. Preliminary results indicate that (110) silicon exhibits higher hole mobility than (100) silicon, consistent with a reduced effective mass. Systematically identifying the relationship between crystal orientation, low temperature mobility, and effective mass may provide a practical route to improving silicon hole-spin quantum devices.
[1] J. P. Wendoloski, J. Hillier, et al., Phys. Rev. B 113, 045302 (2026).
[2] L. Donetti, F. Gámiz, S. Thomas, T. E. Whall, D. R. Leadley, P.-E. Hellström, G. Malm, and M. Östling, J. Appl. Phys. 110, 063711 (2011).
| I am the presenting author | Yes |
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