| Summary: | 碩士 === 國立清華大學 === 物理系 === 104 === In this study we used a 532nm DPSS Laser to heat the D/Ge (100) surface induce a series of thermal reactions; these reactions have been investigated by scanning tunneling microscopy (STM). Each of the reactions depend on surface temperature. One of these thermal reaction is the first order thermal desorption. Under the first order reaction, the surface will have a dramatic change upon a small change of temperature. We can use this change to calibrate temperature measurement at the surface layer.
The initial D/Ge (100) surface prepared in room temperature is disordered, consisting mixed local atomic arrangement. During laser heating, as the surface temperature increases, the surface structure became increasingly ordered; the structure is transformed to another structure. Then as surface temperature rises to ~530 K, the density of dangling bonds increases significantly. The single dangling bonds (SDs) is minority species, only 15% of that of the paired dangling bonds (PDs). As the temperature rises over 550K, Ge-strips appear on the surface, even form 2D Ge-islands. The result of laser heating process to 530 K and over 550 K didn’t discover in previous study.
Among of these thermal reactions, we can use D/Ge (100)-(2×1) thermal desorption reaction to calibrate internally the optical temperature measurement. We have found that the IR Imager’s suitable emissivity set point for the Germanium sample is 0.67 and, the error of the non-contact surface temperature measurement is within.
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