Analysis of the current–voltage characteristics of the Pd/Au Schottky structure on n-type GaN in a wide temperature range

Abstract

We report on the temperature-dependent electrical characteristics of the Au/Pd/n-GaN Schottky diode in the temperature range of 90-410 K. The barrier heights and ideality factors of Schottky diodes were found in the range 0.23 eV and 3.5 at 90 K to 0.97 eV and 1.9 at 410 K, respectively. It was observed that the zero bias barrier height bo decreases and the ideality factor n increases with a decrease in temperature. Such behavior is attributed to barrier inhomogeneities by assuming a Gaussian distribution of barrier heights at the interface. The estimated values of series resistance (R S ) are in the range of 636 at 90 K to 220 at 410 K using Cheung's method. Based on the above observations, the bo , n and R S values are seen to be strongly temperature dependent. The flat-band barrier height bf (T = 0 K) and temperature coefficient α were found to be 0.67 eV and 2.81 × 10 −3 eV K −1 , respectively. Further, the homogeneous barrier height is estimated from the linear relationship between temperature-dependent experimental effective barrier heights and ideality factors and the value is approximately 1.31 eV. The effective Richardson constant is determined to be 20.43 A cm −2 K −2 and is in good agreement with the theoretical value. It is concluded that the temperature-dependent I-V characteristics of the Au/Pd/n-GaN Schottky diode can be successfully explained on the basis of thermionic emission (TE) mechanism with the Gaussian distribution of the barrier heights.

Temperature dependence of 1/f noise in Ni/n-GaN Schottky barrier diode

“…4 shows the/ b0 (in eV) versus ð2kTÞ À1 (in eV À1 ) for Ni/n-GaN SBD in the temperature range 80-300 K. This shows that diode is more homogenous in temperature range 80-150 K and less homogenous in the temperature range 150-300 K. The existence of a double Gaussian distribution in Schottky diode was already experimentally observed by ballastic electron emission microscopy (BEEM). 29,30 Moreover, our experimental findings of double distribution for Ni/ n-GaN Schottky diodes in temperature range 80-300 K are experimentally supported by studies of Yildirim et al, 15 Mamor, 16 Ravinandan et al, 17 and Dogan et al 18 Our exper-imental values of the zero bias mean barrier height, / b0 , and zero bias standard deviation, r s , are in agreement with the studies of Yildirim et al 15 on Ni/n-GaN Schottky diode. Yildrim et al 15 found / b0 and r s as 0.72 eV and 82 meV in the temperature range 100-200 K, respectively, and 1.41 eV and 173 meV in the temperature range of 200-400 K, respectively.…”

“…The temperature dependence of n and / b0 can be explained by the existence of Schottky barrier inhomogeneities at MS interface. [15][16][17][18][19] One of the major reasons behind the origin of Schottky barrier inhomogeneities is that the metal contacts are not epitaxially grown on n-GaN surface, so the interface is not atomically flat but rough. This will result into local variations of the electric field which in turn causes SBH to vary locally.…”

“…Mamor 16 studied various metals (Ni, Pt, Pd) SBDs on n-GaN in temperature range 80-400 K and it was found that inhomogeneities at MS interface can be correlated with the interface state density. Ravinandan et al 17 explained temperature dependence of SBH and ideality factor in Pd/n-GaN SBDs using spatial inhomogeneities at MS interface while Dogan et al 18 investigated temperature dependent currentvoltage (I-V) characteristics with Gaussian distribution of SBH. Arehart et al 19 on the basis of their studies on Ni/n-GaN SBDs have reported that diodes with lower threading dislocation density show nearly ideal Schottky behaviour, while diodes with higher threading dislocation density show a significant deviations from the ideal behaviour.…”

Current-Transport Mechanisms in the AlInN/AlN/GaN single-channel and AlInN/AlN/GaN/AlN/GaN double-channel heterostructures

“…The intersecting voltage values are at nearly 1.5 V and 2.7 V for SC and DC heterostructures, respectively. The intersection behavior of the I-V curves of Schottky barrier diodes (SBDs) measured at different temperatures were discussed by some of the authors in their theoretical and experimental studies [26][27][28][29][30][31]. Among these study, Chand [26] argues that the intersection behaviors of the ln(I)-V curves are an inherent property even of homogeneous SBDs of constant barrier height and are normally hidden due to saturation in current caused by series resistance.…”

“…For larger dimensions, the intersection is shifted to a higher voltage region, where I-V curves are not commonly measured. Ravinandan et al [31] reported that, by experimenting, they found an intersection point in the forward bias I-V characteristics of the Au/Pd/ n-GaN SBDs. They attributed this intersection behavior to the saturation effects of series resistance in each elementary barrier.…”