Modified Interface Properties of Au/n-type GaN Schottky Junction with a High-k Ba0.6Sr0.4TiO3 Insulating Layer

The interface properties of a Au/n-GaN Schottky junction (SJ) were modified by placing a high-k barium strontium titanate (Ba0.6Sr0.4TiO3) insulating layer between the Au and n-GaN semiconductor. The surface morphology, chemical composition, and electrical properties of Au/Ba0.6Sr0.4TiO3 (BST)/n-GaN metal/insulator/semiconductor (MIS) junctions were explored by atomic force microscopy, energy-dispersive x-ray spectroscopy, current-voltage (I-V) and capacitance-voltage (C-V) techniques. The electrical results of the MIS junction are correlated with the SJ and discussed further. The MIS junction exhibited an exquisite rectifying nature compared to the SJ. An average barrier height (BH) and ideality factors were extracted to be 0.77eV, 1.62eV and 0.92eV, 1.95 for the SJ and MIS junction, respectively. The barrier was raised by 150meV for the MIS junction compared to the MS junction, implying that the BH was effectively altered by the BST insulating layer. The BH values extracted by I-V, Cheung's and Norde functions were nearly equal to one another, indicating that the techniques applied here were dependable and suitable. The frequency-dependent properties of the SJ and MIS junction were explored and discussed. It was found that the interface state density of the MIS junction was smaller than the SJ. This implies that the BST layer plays an imperative role in the decreased N-SS. Poole-Frenkel emission was the prevailed current conduction mechanism in the reverse-bias of both the SJ and MIS junction

Analysis of electronic parameters and frequency-dependent properties of Au/NiO/n-GaN heterojunctions

The electrical and frequency-dependent properties of ten Au/NiO/n-GaN heterojunctions fabricated with similar conditions are assessed by I-V, C-V, and G-V measurement methods. In addition, C-f and G-f measurements are conducted in the frequency range of 1 kHz-1 MHz. The electronic parameters are changed from junction to junction even if they are fabricated in the similar way. The calculated barrier height and ideality factor values are fitted by the Gaussian distribution function. Statistical analysis of the data provides the mean barrier height and ideality factor values of 0.84 eV and 2.70 for the heterojunction. Besides, the mean barrier height (Phi(b)), donor concentration (N-d), space charge layer width (W-D), and Fermi level (E-F) are determined from the C-V data and the corresponding values are 1.30 eV, 2.00x 10(17) cm(-3), 8.222 x 10(-6) cm, and 0.018 eV, respectively. The interface state density (N-SS) and relaxation time (tau) are assessed from C-f and G-f measurements. Moreover, the dielectric constant (epsilon'), dielectric loss (epsilon `'), tangent loss (tan delta), and electrical conductivity (sigma(ac)) are determined from C-f and G-f data in the frequency range of 1 kHz-1 MHz with various biases (0.1-0.6 V). epsilon' and epsilon `' are decreased with increasing frequency

Temperature-dependent electrical characteristics and carrier transport mechanism of p-Cu2ZnSnS4/n-GaN heterojunctions

This work explores the temperature-dependent electrical characteristics and carrier transport mechanism of Au/p-Cu2ZnSnS4/n-type GaN heterojunction (HJ) diodes with a CZTS interlayer. The electrical characteristics were examined by current-voltage-temperature, turn-on voltage-temperature and series resistance-temperature in the high-temperature range of 300-420 K. It is observed that an exponential decrease in the series resistance (R-S) and increase in the ideality factor (n) and barrier height (phi(b)) with increase in temperature. The thermal coefficient (K-j) is determined to be -1.3 mV K-1 at >= 300 K. The effective phi(b) is determined to be 1.21 eV. This obtained barrier height is consistent with the theoretical one. The characteristic temperature (T-0) resulting from the Cheung's functions dV/d(lnI) vs. I and H(I) vs. I], is seen that there is good agreement between the T-0 values from both Cheung's functions. The relevant carrier transport mechanisms of Au/p-CZTS/n-type GaN HJ are explained based on the thermally decreased energy band gap of n-type GaN layers, thermally activated deep donors and increased further activated shallow donors

Електричні характеристики переходу Шоткі Au/n-GaN з ізоляційним шаром High-k SrTiO3

Електричні характеристики переходу Шоткі Au/n-GaN (SJ) вдосконалювалися з використанням ізолюючого шару високоміцного титанату стронцію (SrTiO3) в середині шарів Au і n-GaN. Розглянуто електричні властивості Au/n-GaN SJ та Au/SrTiO3/n-GaN метал/ізолятор/напівпровідник (MIS) переходу методами струм-напруга і ємність-напруга. MIS перехід показав вишуканий випрямляючий характер порівняно з SJ. Встановлено, що послідовний опір та опір шунту становлять 30 Ω, 4.69 x 106 Ω та 250 Ω, 2.12 x 109 Ω, відповідно, для SJ та MIS переходу. Розрахункова висота бар'єру і коефіцієнти ідеальності SJ і MIS переходу становили 0.67 еВ, 1.44 і 0.83 еВ, 1.78, відповідно. Більше значення висоти бар’єру було досягнуто для MIS переходу у порівнянні з SJ, що свідчить про те, що висота бар’єру ефективно змінювалася за допомогою шару SrTiO3. Крім того, коефіцієнт ідеальності, висота бар’єру і послідовний опір SJ і MIS переходу оцінювалися за допомогою функції Ченга і порівнювалися між собою. Спостереження показують омічну поведінку в областях з низькою напругою і провідність, обмежену об'ємним зарядом, в областях з вищою напругою у прямому зсуві I-V характеристики для SJ і MIS переходу. Крім того, досліджено механізм провідності зворотного струму витоку SJ і MIS переходу.The electrical characteristics of Au/n-GaN Schottky junction (SJ) were improved by a place of high-k strontium titanate (SrTiO3) insulating layer in the middle of Au and n-GaN. The electrical properties of Au/n-GaN SJ and Au/SrTiO3/n-GaN metal/insulator/semiconductor (MIS) junction were explored by current-voltage and capacitance-voltage techniques. The MIS junction displayed an exquisite rectifying nature as compared to the SJ. The series resistance (RS) and shunt resistance (RSh) were found to be 30 Ω, 4.69 x 106 Ω and 250 Ω, 2.12 x 109 Ω for the SJ and MIS junction, respectively. The estimated barrier height (BH) and ideality factors of SJ and MIS junction were 0.67 eV, 1.44 and 0.83 eV, 1.78, respectively. Higher BH was achieved for the MIS junction than the SJ junction, suggesting the BH was effectually changed by the SrTiO3 layer. Also, the ideality factor, BH and series resistance of the SJ and MIS junction were estimated by employing the Cheung’s function and compared each other. Observations reveal the ohmic behavior at lower voltage regions and space-charge-limited conduction at higher voltage regions in the forward bias I-V characteristic of the SJ and MIS junctions. Also, the reverse leakage current conduction mechanism of SJ and MIS junctions was explored