## 1 Introduction  
Schottky diodes are widely used in the power electronics industry because of their low forward voltage drop and high switching speed [1]. Low voltage switching power supply and DC-DC converter are among the applications that use Schottky diode technology. However, due to its intrinsic characteristic of increased leakage current at elevated temperature, this limits the operating temperature of the device [2]. It is necessary to ensure that the Schottky diode is operated at the specified temperature to avoid thermal runaway effect, which will cause destructive failure of the device [3]. There are a few methods introduced to overcome thermal runaway. One of the methods employed is by using a trench metal-oxide-semiconductor (MOS) structure to suppress leakage current or electric field [4; 5; 6; 7]. At reverse bias condition, the existence of MOS structures causes charge-coupling along the trench sidewall. The depletion region between the two adjacent MOS transistors will merge resulting in current pinch off, hence altering the electric field distribution at the Schottky interface. This, in turn, shifts the peak of the electrical field away from the Schottky interface to the silicon bulk, allowing reduced leakage current for TMBS diodes. It is still not sufficient, however, to totally eliminate thermal runaway due to limited junction temperature.  
To improve this limitation, a new material to replace the conventional metal barrier (titanium silicide (TiSi\({}_{2}\)), cobalt silicide (CoSi\({}_{2}\)), and nickel silicide (NiSi\({}_{2}\))) is sought. Nanostructured carbon or more specifically graphene material is one of the promising candidates for an alternative metal barrier that could help to improve the limitation of junction temperature as it has metallic behavior with excellent electronic and thermal properties [8; 9]. Recently, there have been a number of studies on graphene-silicon Schottky junctions for various applications [10; 11; 12]. In this work, a graphene nanowall (GNW), also called carbon nanowall (CNW), was used as an alternative metal barrier for a TMBS diode. Graphene nanowalls, with their vertically oriented sheets, have been found to have potential areas of application in field emission, energy storage, gas sensing, biosensors, and lithium-ion batteries [13; 14].  
Several methods have been employed to grow a GNW layer, but the most popular method is by plasma enhanced chemical vapor deposition (PECVD) because of its feasibility, the potentiality for large-area production, and lower process temperature compared to other methods [15]. In addition to this, a GNW layer can be grown directly on silicon or a silicon oxide surface without a catalyst, thus eliminating possible additional defects and contamination residing on the silicon surface where the layer of interest is in contact with the silicon.  
In this work, we demonstrate GNW diode leakage behavior at different temperatures on a trench Schottky diode device. I-V test measurement on the forward bias will be used to extrapolate data to obtain Schottky barrier height, ideality factor, and series resistance. All these data will be compared against a standard commercial TiSi\({}_{2}\)-based trench Schottky diode (TiSi\({}_{2}\)-TMBS).