Investigation of surface potential distributions of phosphorus-doped n-BaSi2thin-films by kelvin probe force microscopy

Daichi Tsukahara,Masakazu Baba,Kaoru Toko,Ryota Takabe,Takashi Suemasu

doi:10.7567/jjapcp.3.011403

Abstract

We investigated the surface potential distributions around grain boundaries (GBs) in phosphorus (P)-doped n-BaSi2 thin-films by Kelvin probe force microscopy (KFM) and the crystal planes constituting GBs by transmission electron microscopy (TEM). By KFM measurements, it was found that the GBs in P-doped n-BaSi2 are different from those in undoped BaSi2; undoped n-BaSi2 has a downward band bending around the GBs with barrier heights of approximately 30 meV. In contrast, P-doped n-BaSi2 has an upward band bending with barrier heights of approximately 15 meV. TEM observation revealed that most of the GBs in P-doped BaSi2 are composed of BaSi2 (011)/(0-11) planes. This result is the same as that in undoped BaSi2.

Highlights

BaSi2 has an ideal band gap of approximately 1.3 eV and a large absorption coefficient of 3×104 cm-1 at 1.5 eV [1,2]
This may lead to the upward band bending as shown in Fig. 3 as in heavily Sb-doped n-BaSi2[9], (2) the crystal planes which form grain boundaries (GBs) changed by P doping and thereby the sign of potential barrier height at GBs with respect to the BaSi2 grains changed from undoped ones
We determined the position of GBs in P-doped BaSi2 on Si(111) by AFM and investigated the surface potential distribution around the GBs by Kelvin probe force microscopy (KFM)

Summary

Introduction

BaSi2 has an ideal band gap of approximately 1.3 eV and a large absorption coefficient of 3×104 cm-1 at 1.5 eV [1,2]. These results indicate that a-axis-oriented P-doped BaSi2 was grown on Si(111). This result means that the GBs are negatively charged compared with the grain interiors, suggesting that the upward band bending occurred around the GBs. we evaluated the potential barrier height ΔEGB at GBs by the following Eq (1)

Results

Conclusion