Comparative study of evaporated germanium and silicon films by inelastic electron tunneling spectroscopy

Characterization of Metal Oxide Surfaces and Thin Semiconductor Films by Inelastic Electron Tunneling Spectroscopy

“…Thus, we concluded that the GeH species is predominantly formed in the evaporated Ge films both in a high vacuum (10 -6 Torr) and in an atmosphere of H2O (10 -5 Torr) in the temperature range 20 -150˚C. 21,114,115 A comparison between the tunneling spectra of the Ge and Si films shows that the intensity of νGeH in the tunneling spectra of Ge films is much weaker than that of νSiHx in the tunneling spectra of Si films. On the other hand, the νGe-Ge peak is sharper and stronger than the νSi-Si peak.…”

“…The structures and properties of these thin evaporated semiconductor films have been studied. 20,21,[103][104][105][106][107][108][109][110][111][112][113][114][115][116][117][118][119] Tunneling spectra of oxides grown on Si wafers were also reported. [120][121][122][123][124][125] …”

“…The peaks at 2010 and 570 cm -1 in the tunneling spectra obtained from both types of junctions are assigned to νGeH and δGeH, respectively. 21,114,115 There are no peaks due to GeH2 and GeH3 species. The very strong peaks at 270 cm -1 are due to νGe-Ge.…”

“…These tunneling spectra showed that the peak positions and their relative intensities are independent of the heat treatment. 114,115 Since monohydride (GeH) is stable in this temperature range and dihydride (GeH2) and trihydride (GeH3) are unstable at high temperatures, the presence of GeH seems to be most important in these heated Ge films. Thus, we concluded that the GeH species is predominantly formed in the evaporated Ge films both in a high vacuum (10 -6 Torr) and in an atmosphere of H2O (10 -5 Torr) in the temperature range 20 -150˚C.…”

“…It is assumed that the matrix elements or the cross sections for the νSiHx and νGeHx modes in the tunneling spectra of the Si and Ge films are equal as in the case of the infrared spectra of the hydrogenated amorphous Ge-Si (a-Gex-Si1-x:H) alloys. 21,114,115 The very weak intensity of νGeH in the tunneling spectra of the evaporated Ge films indicates a small number of the GeH species in the films. The similar structural model of a-Gex-Si1-x:H is expected to be applied to very thin (~nm) evaporated Si and Ge films; the H attachment is stronger in Si so that Si-H bonds on the surfaces of the evaporated films are preferred to Si-Si bonds, while the H attachment is weaker in Ge so that Ge-Ge bonds win out on the surfaces.…”