Epitaxy of germanium using germane in the presence of tetramethylgermanium

Epitaxial germanium (Ge) growth from germane (GeH₄) has been investigated in the presence of organometallic tetramethylgermanium (TMGe) in the temperature range of 675-825 °C. Under the growth conditions employed, the growth of Ge is essentially mass-transport limited with an optimum growth temperature of 725 °C. The presence of TMGe does not increase Ge growth rates but lowers background-carrier concentrations in undoped n-type Ge layers. This reduction in background-carrier concentration is more pronounced at higher growth temperatures. In addition, the presence of TMGe yields more abrupt p⁺-n junctions, possibly suggesting the formation of more ``defect-free'' epitaxial growth of Ge from GeH₄ and reduced boron diffusion into n-Ge layers.