Electrical characterization of phosphorus-doped n-type homoepitaxial diamond layers

摘要

Electrical properties of phosphorus (P)-related donors have been investigated for P-doped homoepitaxial diamond layers grown by microwave plasma CVD. Temperature-dependent current-voltage (I-V), capacitance-voltage (C-V) measurements and frequency-dependent C-V measurements have been carried out with lateral dot-and-plane (with ring-shaped gap) Schottky barrier diodes. N-type Schottky junction properties were obtained. The ideality factor and the rectification ratio of the Schottky junction were obtained to be 1.9 and 1.7×10{sup}5 at ±10 V and 473 K, respectively. Frequency-dependent measurements on these Schottky barrier diodes have shown that the capacitance is reduced at high frequency, most likely due to the inability of deep centers to maintain an equilibrium ionization state under a high-frequency modulation. C-V measurements deduced that the net donor concentration was 6.2 × 10{sup}17 cm{sup}(-3) and the corresponding built-in potential was 4.0 eV, when the P concentration was 8.3× 10{sup}17 cm{sup}(-3). Phosphorus electrical activity was 0.75 in the P-doped diamond layer. The carrier thermal activation energy (the donor level) was evaluated to be 0.6 eV from the relation between the net donor concentration and the carrier concentration.