Valense band structure of Gex Si1-x for hole transport calculation

Ying Fu, Kaj Grahn, Magnus Willander

Research output: Contribution to journalArticleScientificpeer-review

24 Citations (Scopus)


We have calculated the hole densities of states and the velocities as functions of energy in strained and relaxed p-type GexSi1-x layers grown on ⟨001⟩ Si substrates. It is shown that the nonparabolic and nonspherical effects are very large in the energy range of (0, 0.2 eV) measured from the heavy hole band edge. Deeper into the valence band, the bands gradually become parabolic and spherical. For most applications, the impurity doping concentration is below 1020 cm-3. For 1020 cm-3 p-type doped Si, the Fermi level is 77.3 meV at 77 K. It is therefore concluded that the nonparabolic and nonspherical effects must be taken into proper consideration when investigating the transport properties of p-type GexSi1-x samples. The calculated data of both relaxed and strained GexSi1-x valence band structures are curve fitted and a data library is built up for further study of the hole transport properties. The mobility and the diffusion coefficient are largely affected when the doping concentration is increased. It is found that at high doping concentration the contributions from the light hole and spin split-off bands become very important, they can become even larger than the contribution from the heavy hole band, even if their densities of states are smaller than that of the heavy hole band.
Original languageEnglish
Pages (from-to)26-31
JournalIEEE Transactions on Electron Devices
Issue number1
Publication statusPublished - 1994
MoE publication typeA1 Journal article-refereed


Dive into the research topics of 'Valense band structure of Gex Si1-x for hole transport calculation'. Together they form a unique fingerprint.

Cite this