Electronic band structure and effective mass parameters of Ge1-xSnx alloys

Abstract

This work investigates the electronic band structures of bulk Ge 1-x Sn x alloys using the empirical pseudopotential method (EPM) for Sn composition x varying from 0 to 0.2. The adjustable form factors of EPM were tuned in order to reproduce the band features that agree well with the reported experimental data. Based on the adjusted pseudopotential form factors, the band structures of Ge 1-x Sn x alloys were calculated along high symmetry lines in the Brillouin zone. The effective masses at the band edges were extracted by using a parabolic line fit. The bowing parameters of hole and electron effective masses were then derived by fitting the effective mass at different Sn compositions by a quadratic polynomial. The hole and electron effective mass were examined for bulk Ge 1-x Sn x alloys along specific directions or orientations on various crystal planes. In addition, employing the effective-mass Hamiltonian for diamond semiconductor, band edge dispersion at the C-point calculated by 8-band k.p. method was fitted to that obtained from EPM approach. The Luttinger-like parameters were also derived for Ge 1-x Sn x alloys. They were obtained by adjusting the effective-mass parameters of k.p method to fit the k.p band structure to that of the EPM. These effective masses and derived Luttinger parameters are useful for the design of optical and electronic devices based on Ge 1-x Sn x alloys. V C 2012 American Institute of Physics.

Growth and applications of GeSn-related group-IV semiconductor materials

“…The operation of n-channel and p-channel Ge 1− x Sn x MOSFETs has been reported [145, 146]. However, the performances are not as high as those expected from the Ge 1− x Sn x material properties [147, 148]. Although clear physical origins of these inadequate performances have not been clarified yet, the inadequate quality of the gate stack structures attributed to the Sn migration, as discussed in section 4, could be one of the reasons for this performance.…”

Formation of high-quality oxide/Ge1−xSnx interface with high surface Sn content by controlling Sn migration

“…At a Sn content of $8%, the conduction band minimum crosses over from the L valley to the C valley, 1 and the electron effective mass significantly decreases at the C point. 5 However, the solid solubility limit of Sn in Ge is $1%, 6 and the surface energy of Sn is smaller than that of Ge. 7 These characteristics induce Sn precipitation and segregation, making it quite difficult to form a Ge 1Àx Sn x layer with high amounts of uniformly distributed Sn.…”

Germanium-tin n-channel tunneling field-effect transistor: Device physics and simulation study

“…The accuracy of the EPM results depends on the match with reported experimental data and the details of the calibration or the EPM calculation can be found in Ref. 42. Due to the introduction of Sn, E G,C and E G,L of Ge 1Àx Sn x decrease as Sn composition increases [see Fig.…”

“…These parameters can be calculated based on the effective masses extracted from the full band E-k plots obtained by EPM. 42 The electron effective masses (transverse effective mass 43 The intrinsic carrier concentration n i is given by…”