Electrical Transport Characteristics of Vertical GaN Schottky-Barrier Diode in Reverse Bias and Its Numerical Simulation

Abstract

We investigated the temperature-dependent reverse characteristics (JR-VR-T) of vertical GaN Schottky-barrier diodes with and without a fluorine-implanted edge termination (ET). To understand the device leakage mechanism, temperature-dependent characterizations were performed, and the observed reverse current was modeled through technology computer-aided design. Different levels of current were observed in both forward and reverse biases for the ET and non-ET devices, which suggested a change in the conduction mechanism for the observed leakages. The measured JR-VR-T characteristics of the non-edge-terminated device were successfully fitted in the entire temperature range with the phonon-assisted tunneling model, whereas for the edge-terminated device, the reverse characteristics were modeled by taking into account the emission of trapped electrons at a high temperature and field caused by Poole–Frenkel emission.

Optimisation of Negative Fixed Charge Based Edge Termination for Vertical GaN Schottky Devices

“…Therefore, due to the formation of vacancies and F-vacancy complexes, the number of F at the interstitial site will reduce leading to a reduction in fixed charge density. Our previous study [ 32 ] demonstrated that only approximately 10% of the implanted fluorine exists as fixed negative charges. Therefore, it is necessary to reduce vacancy concentration and increase the F concentration in interstitial sites.…”

“…First-principle defect calculations carried out within the density functional theory (DFT) [ 27 , 28 ] indicate that the dominant defect configuration of F is negatively charged interstitial with the lowest formation energy in n-GaN whereas is the dominant defect in p-GaN. In vertical GaN devices, this property of F has been utilized to improve the BV by spreading the electric field away from the contact edge [ 29 , 30 , 31 , 32 , 33 ].…”

Study of the Leakage Current Transport Mechanisms in Pseudo-Vertical GaN-on-Silicon Schottky Diode Grown by Localized Epitaxy

“…Figure 5a shows the typical reverse J-V characteristics of the GaN pseudo-vertical SBD. The destructive Breakdwon Voltage BV of the schottky barrier diode is around 80 V, this low voltage capability is mainly related to the absence of edge termination [17,18], and in particular due to expected high electric field at the edges of the Schottky contact. Leakage current in vertical devices has typically been associated with defects in the active layers since the dislocation density is high [11,24], in particular for GaN on Si devices.…”

“…Many researchers have reported that variable range hopping (VRH) by dislocations is the main off-state leakage mechanism in vertical GaN diodes on Si, sapphire and GaN substrates [16]. Others have found that the dominant leakage mechanisms in GaN-on-Si SBDs are different at different reverse biases, and depend on the presence of Edge Terminations (ET) [17,18]. This work aims to understand the carrier transport processes in pseudo-vertical Schottky barrier diodes (SBDs) GaN on Si obtained by selective area growth (SAG).…”

Study of Leakage Current Transport Mechanisms in Pseudo-Vertical GaN-on-Silicon Schottky Diode Grown by Localized Epitaxy

“…Many researchers have indicated that variable range hopping (VRH) facilitated by dislocations serves as the principal off-state leakage mechanism in vertical GaN diodes [16]. Others have reported that the primary leakage process in GaN-on-Si SBDs varies for different reverse biases and is contingent upon the presence of edge terminations (ETs) [17,18]. The goal of this study was to understand the carrier transport processes in pseudo-vertical GaN Schottky barrier diodes (SBDs) on Si obtained by Selective Area Growth (SAG).…”