INSITU INCORPORATION OF AL AND N AND P-N-JUNCTION DIODE FABRICATION IN ALPHA(6H)-SIC THIN-FILMS

Aluminum and nitrogen have been introduced as p- and n-typ dopants, respectively, during chemical vapor deposition (CVD) of alpha-(6H)-SiC substrates. The atomic concentration of each dopant in the films showed a linear dependence on partial pressure of the dopant source gas. The Al species exhibited ideal behavior based on a dilute solution model. Thus elemental Al and / or a complex containing only one Al atom were the principal species which contributed to the incorporation of this constituent. The incorporation of N was greater than expected from the dilute solution theory which implied interaction between N and Si in the SiC. The relationship between ionized dopant concentration (carrier concentration) and the concentration in each dopant source gas was also linear and parallel to its atomic concentration. The ratios of the carrier concentration to the atomic concentration for Al and N were 0.02 and 0.06, respectively. P-n junction diodes were fabricated which exhibited rectification and reverse leakage currents at 100 V of 0.19, 0.75, and 1.3-mu-A at 298, 523, and 623 K, respectively. The turn-on voltage decreased from 2.2 to 2.1 and 1.9 V with each incremental increase in temperature.