2012 Volume 33 Issue 10 Pages 575-582
The hole channel of hydrogen (H)-terminated diamond surface can be linked to adsorption of a specific gas species on the surface. O3, NO2, NO, and SO2 were identified as adsorbates, which induce holes on the H-terminated diamond surface. During NO2 adsorption, hole sheet concentration, ps, saturated at a certain value, however, in the NO2 gas concentration range of>300 ppm, the values were the same. Therefore we determined that the high limit of ps is∼9×1013 cm−2, which is 5.7% of the surface C-H bonds for (001) orientation. X-ray photoelectron spectroscopy investigation showed upward band bending and partial oxidation but no C-N bonds of the H-terminated surface after exposure to air and NO2. We propose a NO2 adsorption/desorption and hole-doping model to explain these experimental results.