Surface morphology, electrical and optical properties n-type doped MOCVD grown GaSb using dimethyltellurium

Dimethyltelluride has been used as a dopant source for GaSb epilayers grown via atmospheric pressure metalorganic chemical vapour deposition (MOCVD). It has been observed that the electron concentration (n) is proportional to the Te partial pressure in the vapour phase, until n saturates at high Te partial pressure. Electron concentrations as high as 1.36 × 10¹⁸ cm^-3 have been measured with imperfect morphology, and as high as 1.22 × 10¹⁸ cm^-3 with excellent, mirror like, morphology. These appear to be the highest electron concentrations reported to date for any MOCVD-growth epitaxial n-type GaSb doped with DMTe and grown at 540 °C with a V/III ratio of 1.4. The absorption spectra of GaSb doped with DMTe show that the heavily doped samples have a less abrupt edge. The absorption coefficient (α) strongly depends on the free carrier concentration. PL spectra of the epilayers are also reported.