Comparative investigation of optical and structural properties of porous SiC
Introduction
It is well known that SiC is promising for substitution of silicon in microelectronics industry, especially in high power, high frequency, and high temperature devices [1]. SiC nanocrystals (NCs) have been studied extensively in the last 10 years as very interesting object for potential application as nanoscale blue light emitters [2]. It was shown later some prospective applications of SiC-based homoepitaxial or GaN-based heteroepitaxial device structures formed on porous SiC (PSiC) substrates with improved quality [3], [4], [5]. Despite the technological progress, the fundamental properties of SiC nanocrystallite structures and methods of its non-destructive characterization are under developed. Thus, the SiC-NC structure investigation and development of characterization techniques are of much interest.
Section snippets
Samples and methods
The PSiC layers were formed by surface anodization of n-type 6H–SiC substrate with resistivity of 0.052 Ω cm and orientation (0 0 0 1) in 3% aqueous solution of HF at dc current densities of 4, 8, 16, 27, and 80 mA/cm2 and process duration of 3 min without external illumination (Table 1). Each sample contained a porous layer and non-porous part. Raman spectra were measured in the backscattering configuration using a Labram–Dilor micro-Raman spectrometer at room temperature and using He–Ne laser
Experimental results and discussion
Typical AFM and SEM images of the PSiC samples are presented in Fig. 1, Fig. 2. Surface roughness of a PSiC layer is estimated from AFM planar and cross-sectional studies. The surface roughness of the PSiC layer increased up to 100–200 nm with increasing of etching current densities (Fig. 1). We estimated the thickness of PSiC layers, presented in Table 1, and an average diameter of pores (100–150 nm) on the base of SEM cross-sectional images (Fig. 2). With increase of etching current densities
Acknowledgment
This work was supported by SIP-IPN, Mexico.
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