Anomalous Temperature Dependence of the Hall Coefficient of Heavily Al-Doped 4H-SiC Epilayers in the Band Conduction Region

Abstract:

We investigate the temperature dependence of the resistivity and Hall coefficient for heavily Al-doped p-type 4H-SiC epilayers with Al concentrations (C_Al) of > 2E19 cm^−3, which are substrates for the collectors of insulated-gate bipolar transistors. The signs of the measured Hall co- efficients (R_H) changed from positive to negative at low temperatures. For epilayers with C_Al values of < 3E19 cm^−3, a negative R_H was observed in the hopping conduction region. In contrast, for epilayers with C_Al values of > 3E19 cm^−3, a negative R_H was observed in not only the hopping conduction region but also the band conduction region, which is a striking feature because the movement of free holes in the valence band should make R_H positive. For an epilayer with C_Al of 1.8E20 cm^−3, the sign of R_H clearly changed three times in the band conduction region. Moreover, the activation energies of the temperature-dependent R_H values were similar to those of the temperature-dependent resistivity in the corresponding temperature ranges, irrespective of the conduction mechanisms (band and hopping conduction).

• Periodical: Materials Science Forum (Volume 1004)
• Pages: 215-223
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.1004.215
• Online since: July 2020
• Authors: Hideharu Matsuura*, Rinya Nishihata, Akinobu Takeshita, Kohei Ogawa, Tatsuya Imamura, Kota Takano, Kazuya Okuda, Atsuki Hidaka, Shi Yang Ji, Kazuma Eto, Kazutoshi Kojima, Tomohisa Kato, Sadafumi Yoshida, Hajime Okumura
• Keywords: Band Conduction, Conduction Mechanism, Hall Coefficient, Heavily Al-Doped 4H-SiC, Resistivity, Sign Inversion of Hall Coefficient

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