This study investigated the temperature dependence of the current-voltage (I-V) characteristics of Al-doped MgxZn1-xO/p-AlGaN junction diodes. The n-type Al-doped MgxZn1-xO (AMZO) films were deposited on p-AlGaN using a radio-frequency (rf) magnetron sputtering system followed by annealing at 700, 800, and 900°C in a nitrogen ambient for 60 s. The n-AMZO/p-AlGaN diode at a substrate temperature of 25°C showed the lowest leakage current in reverse bias. The n-AMZO/p-AlGaN diode with an AMZO annealed at 900°C demonstrated the lowest reverse leakage current. The temperature sensitivity coefficients of the I-V characterizations were obtained at different substrate temperatures (25, 50, 75 100, and 125°C), providing extracted values of 6.4, 7.6, and 5.6 mV/°C in forward bias and −20, 5.6, and 0.8 mV/°C in reverse bias for the AMZO films annealed at 700, 800, and 900°C, respectively. The n-AMZO/p-AlGaN junction diode fabricated with AMZO annealed at 900°C demonstrated the lowest temperature dependence. In addition, the light emission was derived from the forward-biased junction, and near-ultraviolet light emission was evident at all of the p-n diodes. Based on these findings, the n-AMZO/p-AlGaN diodes are suitable for GaN-based heterojunction bipolar transistors (HBTs) and near-ultraviolet light-emitting diodes (LEDs).
A radio-frequency magnetron sputtering technique and subsequent rapid thermal annealing (RTA) at 600, 700, 800, and 900 °C were implemented to grow high-quality Ga-doped MgxZn1-xO (GMZO) epi-layers. The GMZO films were deposited using a radio-frequency magnetron sputtering system and a 4 inch ZnO/MgO/Ga2O3 (75/20/5 wt %) target. The Hall results, X-ray diffraction (XRD), and transmittance were determined and are reported in this paper. The Hall results indicated that the increase in mobility was likely caused by the improved crystallization in the GMZO films after thermal annealing. The XRD results revealed that MgxZn1-xO (111) and MgO2 (200) peaks were obtained in the GMZO films. The absorption edges of the as-grown and annealed GMZO films shifted toward the short wavelength of 373 nm at a transmittance of 90%. According to these results, GMZO films are feasible for forming transparent contact layers for near-ultraviolet light-emitting diodes.
This study investigates the temperature dependence of the current-voltage (I-V) characteristics of Al-doped Mg x Zn 1-x O/p-GaN junction diodes. Specifically, this study reports the deposition of n-type Al-doped Mg x Zn 1-x O (AMZO) films on p-GaN using a radio-frequency (RF) magnetron sputtering system followed by annealing at 700, 800, 900, and 1000 °C in a nitrogen ambient for 60 seconds, respectively. The AMZO/GaN films were thereafter analyzed using Hall measurement and the x-ray diffraction (XRD) patterns. The XRD results show that the diffraction angles of the annealed AMZO films remain the same as that of GaN without shifting. The n-AMZO/p-GaN diode with 900 °C annealing had the lowest leakage current in forward and reverse bias. However, the leakage current of the diodes did not change significantly with an increase in annealing temperatures. These findings show that the n-AMZO/p-GaN junction diode is feasible for GaN-based heterojunction bipolar transistors (HBTs) and UV light-emitting diodes (LEDs).
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