G. Bogdan

Electrical transport and defect spectroscopy of free standing single crystal CVD diamond prepared from methane rich mixtures

Transient photocurrent measurements in the Time-of-Flight (TOF) configuration were used to study the electrical transport in single crystalline diamond layers using a Nd:YAG - pumped OPO (2.7 nsec) laser pulse excitation source working at a wavelength of ∼ 218 nm. The amount of collected charge was measured and the hole and electron drift mobilities were determined at room temperature for natural IIa diamond and intrinsic single crystalline CVD diamond samples. A variation of the laser intensity over several orders of magnitude enabled switching between the so called “small signal TOF” and “space charge limited current” (SCLC) modes. Experiments were done using electrical fields in the range of 0.05-1.2 V/μm.

Electrostatic force microscopy mapping of electrical conductivity of hydrogen-terminated diamond films

A method for mapping the surface conductivity of hydrogen-terminated (H-terminated) diamond on a sub-100nm scale is presented. The measuring technique relies on electrostatic force microscopy imaging of the voltage distribution of a current-carrying H-terminated diamond film. The uniform linear voltage drop in highly conductive H-terminated diamond surface layers indicates that the layers behave as homogeneous, diffusive conductors with a well-defined value of the sheet resistance. On the other hand, we observe conductive as well as insulating regions that coexist for not perfectly H-terminated diamond surfaces with poor electric conductivity.