INVESTIGATION OF THE LEAKAGE CURRENT IN GAN P-N-JUNCTIONS

We report on the fabrication and evaluation of leakage current based o n GaN p-n junctions grown by metalorganic vapor phase epitaxy over sap phire. Si and Mg were used as n- and p-type dopants, respectively. Rea ctive ion etching was used to define mesas of different sizes and meta l ohmic contacts were fabricated. Reverse dark current of 15 pA/mm(2) was measured under -8 V bias at room temperature, and that of 900 pA/m m(2) was measured under -5 V bias at 480 K. Surface leakage along the mesa sidewalls is suggested to be the main source of leakage under a l ow bias voltage, and tunneling effects appear to be the main reason fo r junction breakdown.