Characterization of defects in the drift region of 4H-SiC pin diodes via optical beam induced current

Abstract

SiC based electronic devices are extremely promising candidates for high power, temperature, and radiation applications. However, a variety of defects created during the substrate and subsequent epitaxial growth persists. Many of these defects are electrically active and adversely affect the electrical characteristics of these devices. Determining which defects are the most damaging, how they are created, their structure, and methods for removing them are four basic steps paramount to the creation of reliable SiC based power devices. Here we present optical beam induced current ͑OBIC͒ imaging of various dislocations, stacking faults, and defects, which along with electroluminescence ͑EL͒ imaging reveals the electrical activity and the identifying features of the various defects. A strong correlation is established between the features observed via EL and those seen using OBIC imaging.

Thermal Annealing and Propagation of Shockley Stacking Faults in 4H-SiC PiN Diodes

“…A further description of this setup and procedure is available in the literature. 11 Fig. 1 are the successive EL images of diode D24R (a) prior to and (b) following optical stressing and then (c) following 1 h of heating applied during a series of temperature-dependent IV measurements, with a maximum temperature of 210°C maintained for a period of 3 min on the hot chuck.…”

“…On the contrary, upon terminating at the diode surface, a small region of the SSF starting below the p+ layer, possibly at the n-/p+ interface, and extending only about 10 lm into the n-drift region, appears bright, therefore implying that the incorporation of this defect leads to increases in photoconductivity only within the proximity of the n-/p+ interface and has minimal effects elsewhere, save for the loss of photoconductivity occurring at the partial dislocations bounding the SSFs, which is consistent with previously reported results. 11 The reason for this contradiction in behavior is currently not understood and will require further experimental study.…”

Characterization of Recessed-Gate AlGaN/GaN HEMTs as a Function of Etch Depth

“…Details about the EL imaging technique can be found elsewhere in the literature. 26 The series of images in Fig. 7 shows an optical image of an open-gated HEMT, followed by an EL image of an unetched device, followed by images of devices etched for 45 s, 60 s, and 90 s. The drain bias was 50 V, and the current was $15 mA to 20 mA except for the 90 s point, which was on the order of nA.…”

Electrical and Optical Characterization of AlGaN/GaN HEMTs with In Situ and Ex Situ Deposited SiN x Layers

“…Details about the EL imaging technique can be found elsewhere in the literature. 18 No optical filters were used, so the images depict the entire spectral range of the CCD camera (200 nm to 1100 nm). The EL was collected through an optical fiber and detected via an Ocean Optics HR-4000 spectrometer using a 10 ms integration time, averaged 64 times.…”