Impact Ionization in Ion Implanted 4H-SiC Photodiodes
- PDF / 146,411 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 13 Downloads / 193 Views
1069-D07-12
Impact Ionization in Ion Implanted 4H-SiC Photodiodes Wei Sun Loh1, Eric Z. J. Goh1, Konstantin Vassilevski2, Irina Nikitina2, John P. R. David1, Nick G Wright2, and C Mark Johnson3 1 Electronic and Electrical Engineering, the University of Sheffield, Mappin Street, Sheffield, S1 3JD, United Kingdom 2 School of Electrical, Electronic and Computer Engineering, Newcastle University, Newcastle, NE1 7RU, United Kingdom 3 School of Electrical and Electronic Engineering, the University of Nottingham, University Park, Nottingham, NG7 2RD, United Kingdom ABSTRACT Hole dominated avalanche multiplication and thus breakdown characteristics of ion implanted 4H-SiC p+-n--n+ photodiodes were determined by means of photomultiplication measurements using 325 nm UV light. All the tested diodes exhibited low reverse leakage current and reasonably uniform avalanche breakdown. With avalanche widths of 0.2 µm to 1.5 µm and the capability to measure multiplication factor as low as 1.001, the room temperature impact ionization coefficients were precisely deduced from these 4H-SiC diodes using a local ionization model for electric fields ranging from 1.25 MV/cm to 2.8 MV/cm. The results agree with those reported by Ng et al. and are within the accuracy of both the C-V measurements and electric-field determinations.
INTRODUCTION Silicon Carbide (SiC) has many favorable properties such as a wide bandgap (Eg for 4HSiC = 3.23 eV at 300K), high thermal conductivity, large breakdown electric field strength, high saturated drift velocity, outstanding physical toughness and chemical inertness [1, 2]. All these desirable characteristics make SiC a promising candidate to overcome the performance limitations of much more readily available conventional Silicon (Si) based technology for high temperature, high frequency and high power applications [3-5]. Additionally, SiC is also an attractive alternative to the III- nitride based avalanche photodiodes (APDs) for ultraviolet (UV) detection as SiC APDs exhibit extremely low dark current and good visible blind performance [6, 7] even at elevated temperatures, owing to the low intrinsic carrier concentration and thermal stability. An accurate knowledge of the impact ionization mechanism which governs the multiplication process is crucial in order to determine the device breakdown and thus the optimum device design. Nevertheless, most of the impact ionization results [8-11] reported to date are based on p-n diodes fabricated from heavily doped n-type and p-type 4H-SiC epitaxial structures and they show wide variations. Work by Ng et al. [10] is of particular interest as it is the only report of ionization coefficients extracted using excitations by both short (230 nm) and long (365 nm) wavelengths, thus resulting in more realistic hole and electron initiated multiplication behaviors. In Ng et al.’s work [10], both the multiplication and excess noise characteristics of submicron 4H-SiC diodes were interpreted using a non-local model which
takes into account the dead space effect, non-uniform
Data Loading...
