Diameter dependent thermal sensitivity variation trend in Ni/4H-SiC Schottky diode temperature sensors

Abstract

This report is on the diameter dependent thermal sensitivity variation trend of Ni/4H-nSiC Schottky barrier diode (SBD) temperature sensors. Scaled SBDs of 2, 1.6, and 1.2 mm in diameter were fabricated using standard photolithography process comprising a field plate and a guard ring as edge terminations on the same epitaxial wafer. Taking into consideration the heat loss and power consumption, the thermal sensitivities of the fabricated SBDs were measured in the current range from 1 μA to 50 pA. The temperature was varied from 273 to 473 K in step of 25 K. An authoritative consequence of the present study is the observed increase in thermal sensitivity with the diameter of the fabricated SBDs. An exhaustive investigation confirms that in all diodes, there exist nanosized patches, which assumed to have different barrier heights and hence ascertained to be the main cause of anomalies in thermal sensitivity variation with diode size. Taking into account the effective area of these patches, theoretically fitted I–V curves to experimental data show that the numbers of patches were higher in diode with least size and decrease with the increase in the size of the diode. The corresponding barrier heights of these patches were found to be distributed in a Gaussian like manner at the fabricated Ni/4H-nSiC interface with least standard deviation (σ0) in the diode of maximum size.

Tailoring Surface and Electrical Properties of Ni/4H‐nSiC Schottky Barrier Diodes via Selective Swift Heavy Ion Irradiation

“…Another cause of non‐ideality i.e., the type of current conduction mechanism that dominates among field emission (FE), thermionic field emission (TFE), and TE could be determine by value of characteristics tunneling energy ( E 00 ). As can be seen in Table , value of in both SBDs is less than kT q −1 (26 meV) which emphasized that thermionic emission is the dominant current flow mechanism . Moreover, calculated values of BH lowering due to TFE in both SBDs suggest that, there is rarely any chance of TFE effect on BH alteration and non‐ideality.…”

“…Thereafter, a short dip of the cleaned wafer in dilute (2%) hydrofluoric acid was carried out in order to remove the native oxide from the surface of the sample. Next, to remove moisture completely the wafer was baked for 4–6 h in the oven . In this experiment, shadow mask of Molybdenum was used to: (1) pattern the circular shaped SBDs of diameter 1.6 mm at a distance of 1.2 mm apart; and (2) selectively irradiating the SBDs i.e., irradiated only active area of device and block irradiation in other portions.…”

“…Outstanding properties of SiC i.e., wide band gap, high thermal conductivity, low intrinsic carrier concentration, high breakdown electric field, high chemical inertness, etc., make it promising material to meet the mentioned requirement of power devices. SiC based power devices (e.g., switches and rectifiers), outperform by far the corresponding silicon (Si) ones, and enable arriving otherwise unattainable efficiency levels . In these devices, the push for miniaturization comes from the requirement of smaller assemblies in specific applications that can work like larger ones.…”

400 °C Sensor Based on Ni/4H-SiC Schottky Diode for Reliable Temperature Monitoring in Industrial Environments

“…Forward low-bias behavior of ideal Schottky diodes is conventionally characterized by the thermionic emission (TE) equation, [6,7,8,9,10,11,12,13,31,32,33,34,35,36,37,38], ISD≅AnAST2exp(−ΦBn,normalTVth)exp(VSDnVth).…”

Capacitance roll‐off and frequency‐dispersion capacitance–conductance phenomena in field plate and guard ring edge‐terminated Ni/SiO2/4H‐nSiC Schottky barrier diodes

“…Nickel (2000 Å) was used as the Schottky metal and deposited using an e‐beam evaporation method. After nickel metallization (Schottky metal), again vacuum annealing was performed at 350 °C for 30 min to enhance the adhesion between Ni and 4H–SiC .The contact pad was patterned using Ti/Au metal incorporating a third step of lithography. For isolating the device from environmental conditions, a passivation layer of PECVD oxide of thickness 1 µm was deposited on the active area of the device leaving the contact pads uncovered.…”