Electron cyclotron resonance ion source nitridation of Au/n-GaAs schottky diode and current-voltage characterization

This paper presents the elaboration of the Au/GaN/GaAs Schottky diodes using the ECR N₂ plasma source process at 500°C and its electrical characterization. The substrates of GaAs are n-type doped with N_d= 49×10¹⁵cm^-3. The thin GaN films are prepared by nitridation of GaAs substrates, using the Electron Cyclotron Resonance Ion Source method at 500°C. The Gold (Au) circular contact is deposed on the top face with 0.6mm of diameter. The Ohmic contact is a mixture of Gold and germanium deposited on back face. The structures are elaborated with different GaN thickness (1.5 and 0.7nm). To study the effect of nitridation, a complementary sample without GaN film and heated at temperature of 500°C are also electrically tested. The current-voltage (I-V) curves are investigated at room temperature. The (I-V) characteristics show that the sample with 1.5nm of GaN thickness presents low ideality factor (n) and series resistance (Rs) (1.08, and 82.47μ respectively) compared to the values obtained for samples with 0.7nm of GaN thickness (1.54, 640μ). These parameters are estimated equal to (1.21, 88.8μ) for sample heated without GaN film and (1.23, 39.24μ) for sample without GaN film. So, we can deduce that the nitridation using the ECR ion source is an interesting process allowing the passivation of GaAs surfaces. Indeed, the electrical parameters are improved when the GaN thickness increases.