Low Temperature Fabrication of Diamond Films by CVD Method with Laser Induced Surface Reaction

设计并制造了一种用于热解吸和激光诱导解吸的新型装置。该装置具有4种入射窗口(入射角度：0-60o)、XYZθ样品台(检测角度：0-80o)、飞行时间质谱仪和/或四极质谱仪，以及高达1400oC的样品加热系统。样品表面改性的加药系统是通过热W管的热裂解系统，由于热W管内壁上的气体分子可以解离，因此取代了热W管的一部分。因此，我们可以选择任何一种方法来控制样品表面的终止，利用热样品表面分子的热解离或在热裂解系统中产生的原子通量来控制样品表面的终止。使用该装置进行热脱附和激光诱导脱附，样品表面的悬挂键通过1300K Sam…上的氢的热解离来终止更多。然后，从D-端表面检测到了氚分子的热脱附谱。根据热脱附谱的结果确定了样品表面的终止结构，并在此基础上利用脉冲激光(基波-4次谐波)对样品表面进行了激光诱导脱附谱的检测。尝试测量了氢端、CO和CO2在O端金刚石晶体中的脱附。将样品加热到2 0 0℃解吸物理吸附的H2O和/或CO后，用不同波长和能量密度的激光脉冲照射样品。在基波、二次和三次谐波的情况下，我们没有检测到任何解吸谱。虽然我们在四次谐波的情况下可以检测到脱附光谱，但这不是由于激光在表面键合处的反应引起的脱附，而是由于激光脉冲在金刚石晶体中的缺陷处的吸收而导致的样品加热的热脱附。较少

The novel apparatus was designed and manufactured for thermal desorption and laser induced desorption. This apparatus has 4 kinds of inlet window through which laser beam can irradiate onto the sample (incident angle : 0-60o), XYZθ sample stage (detection angle : 0-80o), time-of-flight and/or quadrupole mass spectrometer, and sample heating system up to 1400oC. The dosing system, by which the sample surface can be modified, is the thermal cracking system through hot W tube which was replaced as a part of gas introduction tube, since the gas molecule can be dissociated on the inner wall of hot W tube. Therefore, we can choose either method to control the sample surface termination, using the thermal dissociation of molecules on hot sample surface or atomic flux generated in thermal cracking system.Using this apparatus both for thermal desorption and for laser induced desorption, the dangling bonds on the sample surface was terminated by the thermal dissociation of deuterium on 1300K sam … More ple. Then, the thermal desorption spectrum of deuterium molecules was detected from the D-terminated surface. The termination structure of sample surface after dosing was confirmed by the result of thermal desorption spectra.On basis of the results and speculation of thermal desorption measurement, laser induced desorption spectrum was detected using Nd : YAG pulse laser (fundamental - 4th harmonic wave). H2 desorption of H-terminated, CO and CO2 from O-terminated diamond crystal tried to be measured. After the sample was heated up to 200℃ to desorb physiabsorbed H2O and/or CO, a variety of lased wavelength and energy density of laser pulses were irradiated onto the sample. In case of the fundamental, 2nd, and 3rd harmonic wave, we could not detect any desorption spectra. Although we could detect desorption spectra in case of the 4th harmonic wave, it was not due to the desorption by the laser induced reaction at the surface bond, but due to the thermal desorption by the sample heating as a result of the absorption of laser pulse at the defects in diamond crystals. Less