Hole traps profile and physical properties of deep levels in various homoepitaxial diamond films studied by isothermal and deep level transient spectroscopies

Defects involving hole traps in diamond are investigated with Fourier Transform Deep Level Transient and Isothermal Spectroscopies in several Boron doped diamond films epitaxially grown on Ib substrates in our own reactor, either with or without oxygen in the gas mixture. It is shown that both pre- and post-treatments can stabilize a continuous distribution of traps which was not necessarily present initially. The ionization energy and capture cross section of each trap is determined and compared to previous experimental and theoretical data. From deep trap profiling, it is shown that concentrations are all decreasing below 1015 cm− 3 beyond about 250 nm below the interface with the Schottky metal. All these traps do not exist in epilayers prepared with oxygen in the gas mixture. This set of properties strongly suggests that hydrogen is involved in traps, probably associated with either structural defects or Boron.

Research Highlights
► In MWPCVD diamond, holes traps stabilized after either pre- or post treatments.
► Ionization energies of holes traps lie in the range 0.7–1.6 eV.
► Concentration profiles of holes traps in diamond shows an inwards decreasing trend.
► Holes traps are likely due to defective sites in which hydrogen atom is present.
► Holes traps are suppressed in diamond epilayers prepared with 0.25% of oxygen.