Electrical and structural characteristics of Ge-doped GaN thin films and its hetero-junction diode made all by RF reactive sputtering

The Ge-x-GaN thin films were grown on Si (100) substrates by RF reactive sputtering technology with single cermet targets at the Ge/(Ge + Ga) molar ratios of x = 0, 0.03, 0.07 and 1. The Ge-x-GaN films had a wurtzite structure with a preferential (101¯0) plane. The SEM images showed that Ge-GaN films were smooth, continuous, free from cracks and holes, and possessed grains in nanometer-size. All Ge-x-GaN films remained as n-type. While the highest conductivity was found to be 1.46 S cm−1 in Ge-0.03-GaN film due to the highest carrier concentration of 2.55 × 1018 cm−3. Additionally, we made the n/p diodes with Ge-doped GaN films as n-type layers deposited on Si (100) substrate as p-type layer using by RF reactive sputtering technique. Their electronics characteristics were evaluated in terms of the barrier height, ideality factor, and series resistance.