Effect of Co-60 gamma-ray irradiation on electrical properties of Ti/Au/GaAs1-xNx Schottky diodes

Current-voltage (I-V), capacitance-voltage-frequency (C-V-f) and conductance-voltage-frequency (G/ω-V-f) measurements at room temperature are used to study 50 kGy 60Co γ-ray electrical properties irradiation dependence of Ti/Au/GaAs1−xNx Schottky diodes with 0.2%; 0.4%; 0.8% and 1.2% nitrogen dilution. This γ-ray irradiation induces a permanent damage that has increased ideality factor and series resistance for all samples. It was accompanied by a decrease in Schottky barrier height with nitrogen content up to 0.4%N and remained constant thereafter. Radiation was also found to degrade the reverse leakage current. At high frequency (1 MHz), capacitance and conductance decreased after radiation due to a decrease in net doping concentration. Interface state density and series resistance were determined from C-V-f and G/ω-V-f characteristics using Hill-Coleman methods. Interface states density exponentially decreased with increasing frequency confirming the behavior of interface traps response to ac signal. Series resistance increases after irradiation is attributed to carrier's removal effect and mobility degradation. It has two peaks in the accumulation and inversion region for some diodes (0.4%N, 0.8%N). γ-ray irradiation produced traps levels and recombination centers that reduce relaxation time. An increase in %N content can impede irradiation damage with even some compensation when the percent of diluted nitrogen is high (1.2%N)

Growth parameter investigation of Al(0.25)Ga(0.75)N/GaN/AlN heterostructures with Hall effect measurements

WOS: 000258875200008Hall effect measurements on unintentionally doped Al(0.25)Ga(0.75)N/GaN/AlN heterostructures grown by metal organic chemical vapor deposition (MOCVD) were carried out as a function of temperature (20-300 K) and magnetic field (0-1.4 T). Magnetic-field-dependent Hall data are analyzed using the quantitative mobility spectrum analysis (QMSA) technique. The QMSA technique successfully separated electrons in the 2D electron gas (2DEG) at the Al(0.25)Ga(0.75)N/GaN interface from other 2D and 3D conduction mechanisms of the samples. 2DEG mobilities, carrier densities and conductivities of the investigated samples are compared at room temperature and low temperature (20 K). For a detailed investigation of the 2DEG-related growth parameters, the scattering analyses of the extracted 2DEG were carried out for all of the samples. Using the results of the scattering analyses, the relation between the growth and scattering parameters was investigated. Increments in the interface roughness (IFR) are reported with the increased GaN buffer growth temperatures. In addition, a linear relation between the deformation potential and interface roughness (IFR) scattering is pointed out for the investigated samples, which may lead to a better understanding of the mechanism of IFR scattering.State of Planning Organization of TurkeyTurkiye Cumhuriyeti Kalkinma Bakanligi [2001K120590]; TUBITAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [104E090, 105E066, 105A005]; Turkish Academy of SciencesTurkish Academy of SciencesThis work is supported by the State of Planning Organization of Turkey under Grant no. 2001K120590 and by TUBITAK under Project nos. 104E090, 105E066 and 105A005. One of the authors (Ekmel Ozbay) acknowledges partial support from the Turkish Academy of Sciences