Lifetime of holes determination in 4H-SiC using two-photon optical beam induced current method

Abstract

Wide bandgap semiconductors such as silicon carbide, gallium nitride and diamond have been recently investigated in order to replace silicon in the power electronic domain. In this paper, silicon carbide devices are studied using an optical method. It consists on illuminating a reverse biased junction with a laser beam with an appropriate wavelength, and then measuring the induced current due to the photon absorption. According to the wavelength, one-or two-photon absorption is triggered when photon energy is respectively higher or lower than the semiconductor bandgap. In the latter case, the probability of electron hole pair (EHP) generation is very small, which leads to use a powerful incident beam. In this paper, two-photon generation is used in order to determine the lifetime of minority charge carriers in N doped 4H-SiC. The incident beam is a pulsed green source with a wavelength of 532 nm and a high power density that can reach up to 6 GW.cm -2 . Test devices are PN diodes protected by a junction termination extension (JTE). Results show a hole's lifetime of 730 ns.

OBIC technique applied to wide bandgap semiconductors from 100 K up to 450 K

“…Referring to equation (4), this value is the inverse of L dp , so the diffusion length of the holes is then 14.7 μm. Using equation (5) with hole mobility of 115 cm 2 .V -1 s -1 , the lifetime of holes found is of 730 ns [12]. This value of hole lifetime is in good agreement with the results of Ivanov published in 1999 using the OCVD method (680 ns at 300 K) [13].…”

SiOC-Based Strain Gauge with Ultrahigh Piezoresistivity at High Temperatures

“…For 4H-SiC, electron mobility is 4 times higher than that of the holes when parallel to the c -axis but is of equal magnitude when parallel to the c -axis. On the other hand, 3C-SiC is predominantly driven by electrons with mobility 8 times larger than hole mobility in either orientation. − For graphitic carbons with high tortuosity, like the samples synthesized in this work, the stacking is not explicitly defined, making it difficult to fully understand the probability of the coexistence of charge carriers. The work of Ramadin suggested that the carbon-based composites have charge carriers that transition from p- to n-type as the carbon content increases with a threshold of ∼18% …”