Grain orientation and electrical properties of polycrystalline germanium after laser annealing

Abstract

The grain growth orientation and electrical properties of Ge films on Si substrates deposited by chemical vapor deposition (CVD) after laser annealing with various laser powers were examined using X-ray diffraction (XRD), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Hall-effect measurement. The growth orientation of polycrystalline Ge (poly-Ge) films is significantly affected by the laser power. When the laser power was increased to 3 W, the Ge grain growth in the lateral direction was inclined toward directions, 〈001〉 and 〈111〉. The shape of the Ge grains gradually transformed from columnar to equiaxed, and their surface became rougher with increasing laser power. The carrier mobility and work function (WF) gradually increased to 48.1 cm2 V−1 s−1 and 4.93 eV, respectively, at a laser power of 3 W. These results indicate that the degree of laser power affects the crystallinity, grain orientation, carrier mobility, carrier concentration, and WF of Ge films subjected to laser annealing. This is useful for developing high-efficiency Ge-based integrated circuits devices.