High resolution Laplace deep level transient spectroscopy of p‐type polycrystalline diamond

Abstract

High resolution Laplace deep level transient spectroscopy (LDLTS) has been used to characterise deep electronic states in the band gap of polycrystalline p‐type diamond. The thin diamond films were grown by the hot‐filament chemical vapour deposition (HFCVD) technique on p‐type and n‐type Si for the formation of the Schottky and p–n diodes respectively. The B concentration in the diamond films ranged from 7 × 1018 cm–3 to 7 × 1021 cm–3. Conventional capacitance DLTS showed a fairly narrow peak at about 180 K from the diamond grown on p‐type Si, but further analysis with LDLTS shows that this peak originates from a complex defect with up to three hole emission rates. In the case of the Schottky diode, these emission rates do not vary much with temperature which indicates that they may be due to the presence of an extended defect, where the valence band itself is changing its profile as the traps capture more carriers. LDLTS of a similar trap in the diamond grown on n‐type Si also shows three emission rates, which do not vary as expected with temperature. The results are discussed in terms of defects existing in the strain fields of grain boundaries, and exhibiting non point‐defect like properties. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Effect of doping on electronic states in B-doped polycrystalline CVD diamond films

“…The second scenario could be that the level E1 is grain-boundary-related states. This is a reasonable suggestion since it has been only reported in polycrystalline diamond [47][48][49], although this has not been proven. In this case, the trap distribution will be very inhomogeneous and the defects may be sufficiently closely spaced that the presence of a filled trap will reduce the likelihood of a neighbouring empty trap capturing a hole.…”