Capacitance–voltage studies of Al-Schottky contacts on hydrogen-terminated diamond

The electrical properties of Al contacts on hydrogen-terminated diamond have been characterized. Capacitance–voltage experiments were carried out in order to obtain further insight into the origin of the Schottky contact behavior of Al. Schottky diodes with different areas and peripheries were fabricated and analyzed. We have found that the capacitance of these structures is not proportional to the area but to the length of the contact periphery, supporting the two-dimensional nature of the surface charge layer in hydrogen-terminated diamond. A model based on the negative electron affinity of hydrogen-terminated diamond and the work function of Al is used to explain the in-plane capacitance of the Al Schottky contacts.