Abstract
We report on the structural, electrical, and transport properties of high quality CVD-fabricated n-GaN nanorods (NRs)/p-Si heterojunction diodes. The X-ray diffraction (XRD) studies reveal the growth of hexagonal wurtzite GaN structure. The current–voltage (I–V) characteristics of the n-GaN NRs/p-Si heterojunction were measured in the temperature range of 300–475 K. The ideality factor (n) and zero-bias barrier height (ϕB0) are found to be strongly temperature-dependent. The calculated values of ϕB0 are 0.95 and 0.99 eV according to Gaussian distributions (GD) and modified Richardson for GD, respectively, which are in good agreement with the band offset of GaN/Si (0.95 eV). A Richardson constant of 37 cm−2 K−2 was obtained from the modified Richardson plot, which is close to the theoretical value for p-Si (32 cm−2 K−2). The Gaussian distributions (GD) of inhomogeneous barrier height (BHs) and modified Richardson for GD of BHs with TE have also been used to explain the obtained transport properties.
Highlights
Gallium nitride (GaN)-based-devices have drawn huge attention for future optoelectronic applications due to their unique properties, including high electron mobility, high thermal conductivity, and excellent thermal stability.[1,2] The wide bandgap and high breakdown voltage of GaN are crucial to ensure the functionality of the electronic devices at higher temperatures.[2,3] Owing to the lack of native substrates, GaN-based devices are grown alternatively on various substrates such as Al2O3, SiC, and Si.[3,4,5] Among those substrates, the growth of GaN on Si is of signi cant interest in terms of processing, thermal conductivity, integration, and low cost.[6]
The relatively sharp diffraction peaks in the X-ray diffraction (XRD) spectra indicated the growth of highly crystalline GaN nanorods with wurtzite structure
Using the thermionic emission (TE) model, the ideality factor (n) and barrier height (BH) of the heterojunction device were determined from the forward I–V curves under dark conditions
Summary
It is of great importance to understand the nature of electrical transport through GaN/Si heterojunctions. In order to improve the performance of devices, it is neccessary to study the electrical characteristics of GaN/Si Schottky interfaces at different temperatures. A rigorous analysis of the current– voltage (I–V) characteristics of the GaN/Si heterojunction diodes at different temperatures provides detailed information on the current ow through a single junction and the nature of the barrier formation at GaN/Si interfaces.[18,19,20,21] there have been few previous studies on electrical transport through GaN/ Si heterojunction diodes.[12,21,22] For example, Bhat et al.[11] studied the impact of nitridation on the electrical properties of the nGaN/p-Si heterojunction. Xu and co-workers investigated the I–V–T characteristics of n-GaN/n-Si heterojunctions at different temperatures (18–400 K) and they reported an ideality factor of 10.23 Recently, Tuan et al.[24] studied the electrical properties of pGaN/n-Si at a testing temperature of (300–450 K) and they estimated a Schottky barrier height in the range 0.5 to 0.62 eV. The obtained parameters, including ideality factor diode, barrier height (BHs), at-band barrier height and Richardson constant, have been extracted from the thermionic emission and discussed
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