Application of UV photoluminescence imaging spectroscopy for stacking faults identification on thick, lightly n-type doped, 4°-off 4H-SiC epilayers

N Thierry-Jebali,C Kawahara,T Miyazawa,H Tsuchida,T Kimoto

doi:10.1063/1.4915128

Abstract

This paper deals with the description and the application of an original photoluminescence (PL) imaging technique on thick, lighly n-type doped 4H-SiC epilayers for in-grown stacking fault (SF) identification. This technique, call “photoluminescence imaging spectroscopy” (PLIS), compares different PL imaging pictures in order to create a new picture which displays the location and an approximation of the maximum photoemission wavelength of SFs at room temperature. Five types of SF have been detected and identified by PLIS on two different wafers. The origin of SF type modification during the growth is also discussed in this work.

Highlights

The excellent intrinsic properties of Silicon Carbide (SiC) as a wide band gap semiconductor make possible the development of the forthcoming electronic devices for high voltage, high temperature and high frequency applications.[1,2] For SiC power devices with a blocking voltage higher than 10 kilovolts, bipolar devices, such as PiN diodes, Bipolar Junction Transistors or thyristors are needed.Benefits on the on-state resistance are expected for bipolar devices owning to the effect of conductivity modulation.[3,4]Despite the enthusiasm of developing very high voltage devices, the industrial development ofSiC bipolar is facing some problems
The scattering of L e is high for SF4 type defect which means that this defect was formed in an advance state of the epilayer growth or at the initial stage of the the PL measurement
On EPI1 wafer, four SF2 types defects have been observed. Three of these have been characterized by low temperature (LT) PL spectroscopy and exhibit similar behavior as the spectrum reported on Figure 7

Summary

INTRODUCTION

The excellent intrinsic properties of Silicon Carbide (SiC) as a wide band gap semiconductor make possible the development of the forthcoming electronic devices for high voltage, high temperature and high frequency applications.[1,2] For SiC power devices with a blocking voltage higher than 10 kilovolts, bipolar devices, such as PiN diodes, Bipolar Junction Transistors or thyristors are needed. One of these is the degradation of bipolar devices during operation.[5,6,7] it has been observed that a forward bias on a p-n junction can induce the formation and motion of a single Shockley-type Stacking Fault (SF) through transformation of a Basal Plane. Since the different types of SF into 4H-SiC act as a quantum-well,[8] the generation of SF decreases the lifetime and increases the differential resistance. This phenomenon is called “Forward Voltage Drift” (FVD). At the beginning of any process improvement, there is the characterization of the nature and the location of in-grown SFs. Currently, many techniques are available for this purpose. The idea of PLIS is to make a spectroscopic picture of the sample from different UV-PL imaging pictures taken at different output filters (located before the CCD camera)

EXPERIMENTAL DETAILS

DESCRIPTION OF THE PHOTOLUMINESCENCE IMAGING SPECTROSCOPY

Identification of in-grown of SFs by PLIS

Observation of the SF type modification by PLIS

CONCLUSION