Spectral dependende of the photoconductivity of varizon structures of the type Ge$_x$Si$_{1-x}$, obtained by diffusion technology

By diffusion doping, a graded-gap structure was obtained inner side of the silicon surface, type Ge$_x$Si$_{1-x}$. Elementary analysis of the samples showed that the concentration of silicon (in atomic percent) was 64.5%, germanium – 26.9%, oxygen – 5.9%, and others – 2.7%. In the spectral dependence of the photoconductivity, a noticeable increase in the photocurrent begins at $h\nu$ = 0.75–0.8 eV, which approximately corresponds to the band gap of the Ge$_{0.27}$Si$_{0.73}$ material. The development of a diffusion technology for obtaining graded-gap structures Ge$_x$Si$_{1-x}$ will make it possible to develop photodetectors with an extended spectral sensitivity range.