ABSTRACT: A review of current issues in SiC device processing technology is
followed by a critical assessment of the current state-of-the-art and
future potential for SiC power devices. Material quality, ion
implantation, the SiC-SiO<sub>2</sub> interface and the thermal
stability of contacting systems are all identified as requiring further
work before the full range of devices and applications can be addressed,
The evaluation of current device technology reveals that SiC Schottky
and PIN diodes are already capable of increased power densities and
substantially improved dynamic performance compared to their Si
counterparts. Although direct replacement of Si devices is not yet
economically viable, improvements in system performance and reductions
in total system cost may be realised in the short term. Widespread use
will, however, require continued improvements in wafer quality while
costs must fall by a factor of ten. Finally, the development of new and
improved packaging techniques, capable of handling increased die
temperature and high thermal cycling stresses, will be needed to fully
exploit the potential of SiC
IEE Proceedings - Circuits Devices and Systems 05/2001; · 0.36 Impact Factor
ABSTRACT: Edge termination of Schottky barrier diodes has been achieved using 30 keV Ar+ ions implanted at a dose of 1×1015 cm−2. The reverse-bias leakage current is reduced by 2 orders of magnitude following postimplant annealing at a temperature of 600 °C. The thermal evolution of the implantation induced defects was monitored using positron annihilation spectroscopy and deep-level transient spectroscopy. Two distinct defect regions are observed using the positron technique. The depth of the first is consistent with the range of the implanted Ar+ ions and consists of clustered vacancies. The second extends to ∼250 nm, well beyond the range of the incident ions, and is dominated by point defects, similar in structure to Si–C divacancies. An implant damage related deep level, well defined at Ec−Et=0.9 eV, is observed for both the as-implanted and the 600 °C annealed sample. The effect of annealing is a reduction in the concentration of active carrier trapping centers. © 2000 American Institute of Physics.
Journal of Applied Physics 04/2000; 87(8):3973-3977. · 2.17 Impact Factor
ABSTRACT: A simple ion-implanted bipolar transistor technology in 4H-SiC is presented. Suitable for both high-voltage vertical devices and lateral high-temperature transistors (for circuit applications), the technology is based on an implanted boron p-well with nitrogen and boron (or aluminium) implanted n+ and p+ regions respectively. The effects of base doping and carrier lifetime on device performance have been studied using TCAD techniques. It is shown that understanding the strong variation of carrier concentration with temperature (due to deep activation levels) and applied field (so-called field ionization) is critical in device design optimisation. The effects of post-implant anneal conditions on the physical and electrical characteristics of the junctions are investigated. It is shown that annealing can remove much of the damage induced by high dose nitrogen implantation but that residual damage is still present. The electrical characteristics of simple BJT transistors with breakdown voltages in excess of 1000V and common-emitter gains of ∼2 is related to the level of such residual damage.
MRS Proceedings. 12/1999; 622.
ABSTRACT: The suitability of SiC p-n junction and Schottky varactor diodes
for high frequency applications is demonstrated. It is shown that such
devices are capable of operating at high biases (over 130 V)-offering
greater power density, impedance and operating temperature compared to
conventional GaAs or Si varactors. The limitations induced by relatively
high contact resistivities are evaluated in terms of applications at 10
High Performance Electron Devices for Microwave and Optoelectronic Applications, 1999. EDMO. 1999 Symposium on; 02/1999
ABSTRACT: The edge termination of SiC by the implantation of an inert ion species is used widely to increase the breakdown voltage of high power devices. We report results of the edge termination of Schottky barrier diodes using 30keV Ar+ ions with particular emphasis on the role of postimplant, relatively low temperature, annealing. The device leakage current measured at 100V is increased from 2.5nA to 7μA by the implantation of 30keV Ar+ ions at a dose of 1×1015 cm−2. This is reduced by two orders of magnitude following annealing at 600°C for 60 seconds, while a breakdown voltage in excess of 750V is maintained. The thermal evolution of the defects introduced by the implantation was monitored using positron annihilation spectroscopy (PAS) and deep-level-transient spectroscopy (DLTS). While a concentration of open-volume defects in excess of 1×1019cm−3 is measured using PAS in all samples, electrically active trapping sites are observed at concentrations ∼1×1015cm−3 using DLTS. The trap level is well-defined at Ec−Et = 0.9eV.
MRS Proceedings. 12/1998; 572.
ABSTRACT: The eects of post-implantation annealing on the electrical characteristics of Ni 4H-SiC Schottky barrier diodes terminated using self-aligned Ar ion implantation have been investigated. Results show that the Ar edge termination may be modelled as a shunt linear resistive path at low to moderate reverse bias levels and at low forward bias levels. Low temperature (400±700°C) annealing is shown to increase the equivalent resistance of the edge termination by two orders of magnitude without signi®cant eect on the breakdown voltage. Annealing temperatures above 600°C are, however, shown to degrade the on-state performance. A breakdown voltage of 1530 V was achieved on the implanted and annealed samples, representing 90% of the theoretical parallel plane breakdown voltage. Temperature dependent measurements, made over the temperature range 25±400°C show that the equivalent resistance of the edge termination is thermally activated with an exponential temperature coecient of)0.02 K À1 . Behaviour at moderate forward bias levels is typical of thermionic emission whilst operation at high forward bias is dominated by a linear series resistance which shows a quadratic temperature dependence, increasing by a factor of 6 over the range 25±400°C.