Abstract:
Heteroepitaxial Ge or Ge$_{1-x}$Sn$_x$ layers were grown by hot-wire chemical vapor deposition on Si(001) substrates doped heavily with a donor (As or Sb) impurity. The same layers were also grown on high-resistance Si(001) substrates for comparison. The depth profiles of carrier concentration were measured in both types of layers using the capacitance-voltage method, and carrier mobilities were measured additionally by the Hall effect method in layers on high-resistance silicon. It was found that the layers grown on high-resistance substrates were $p$-type, while the layers grown in the same regimes on heavily doped substrates were $n$-type with electron concentration $n$ = (4–9)$\cdot$10$^{16}$ cm$^{-3}$ in Ge layers and GeSn $n$ = (2–4)$\cdot$10$^{17}$ cm$^{-3}$ in GeSn layers. It was established experimentally and theoretically that the effect of autodoping of Ge and GeSn layers is lacking in the hot-wire chemical vapor deposition method. In our view, the growth of $n$-type Ge and GeSn layers on $n^+$-Si(001) substrates doped heavily with a donor (As or Sb) impurity is associated with the segregation of this impurity in the process of growth of a buffer Si layer and its subsequent incorporation into growing Ge or GeSn layers.
Fulltext:
PDF file (144 kB)