P. Muret et al., Deep level spectroscopy in homoepitaxial diamond films studied from current transients in Schottky junctions, PHYS ST S-A, 174(1), 1999, pp. 129-135
The electrical response of Schottky junctions made on boron doped homoepita
xial diamond films is investigated. Current transients due to the release o
f holes in the valence band from deep level traps are detected and analysed
. The homoepitaxial layers grown by microwave plasma decomposition of a ver
y small percentage of B2H6 mixed with CH4 in hydrogen receive ohmic Mo2C co
ntacts. Rectifying contacts are achieved either with aluminium or erbium af
ter suitable pre- and post-treatments. A rectifying ratio of three orders o
f magnitude can persist up to 500 degrees C and makes deep level transient
spectroscopy (DLTS) possible, A deep level at (1.30 +/- 0.10) eV above the
valence band is detected and seems to be common to various diamond crystals
. Another deep level at (1.14 +/- 0.05) eV above the valence band exists on
ly if an oxygen plasma treatment is applied to the sample before the Schott
ky contact deposition. Thermal capture cross-sections are also deduced.