Epitaxial Growth and Characterization of Self-Doping ${\rm Si}_{1-{\rm x}}{\rm Ge}_{\rm x}{\rm/Si}$ Multi-Quantum Well Materials

This paper presents self-doping Si_1-xGe_x/Si multiquantum wells (MQWs) with35 nm buffer layers where self-doping occurs to allow free carriers in the quantum well. The film grown through ultra-high vacuum chemical vapor deposition method can easily achieve a good lattice quality. The crystal lattice is verified through scanning electron microscopy, X-ray diffraction,and secondary ion mass spectrometry. Unique structures are applied in the Temperature Coefficient of Resistance (TCR) measurement to obtain electrical characteristics of MQWs. The TCR of Si_0.65Ge_0.35/Si obtained in the experiment is about-2.5%/K at 20 °C, which meets the requirements of a thermistor. The TCR decreases from 2.5%/K to 1.1%/K as the size of the MQWs increases from 100 μm×100 μm to 400 μm×400 μm. Annealing is necessary for the formation of an ohmic contact between electrodes and high contact layers.