Thermal Oxide Desorption Research Articles

The kinetics of adsorption and thermal desorption of NO on stepped Pt single crystal surfaces

The kinetics of adsorption and thermal desorption of nitric oxide on Pt field emitter surfaces has been studied by means of pulsed field desorption mass spectrometry (PFDMS). Adsorption on the high index planes with terraces of (111) orientation occurs molecularly with high initial sticking probabilities S=0.65,...,0.9. By varying the repetition frequency of the desorbing field pulses, i.e., by varying the field free reaction time tR (100 μs to 1 s), the mean lifetimes before thermal desorption of the NOad have been measured. The temperature dependence of the mean lifetimes has been evaluated. An activation energy of 139 kJ/mol and a preexponential of 3.8×10−15 s are found. These rate parameters are dominated by adsorption at step sites as verified on the basis of a model comprising multiple state adsorption and desorption. Dissociation of NOad has not been observed on stepped Pt(111), but has been on stepped Pt(100).

InP substrate protection and cleaning in liquid phase epitaxy

The interest in single mode lasers for the 1.3–1.55 μm wavelength region prepared by liquid phase epitaxy requires the growth onto non-planar structured InP substrates. A technique for substrate protection to eliminate thermal degradation prior to growth, together with a thermal oxide desorption, is shown to be very effective for this purpose. Characterization of the InP+Sn protection system and results of substrate protection with different techniques are reported. The effectiveness of the method is demonstrated by SEM observations, X-ray double crystal diffraction measurements and results on DH broad area lasers.

Dynamics of the laser-induced thermal desorption of nitric oxide from a platinum foil

The internal and translational energy distributions of nitric oxide, which was desorbed from a cold polycrystalline platinum foil by laser-induced thermal desorption, were measured using a laser-excited fluorescence, time-of-flight technique. Under irradiation conditions which are estimated to produce a maximum surface temperature of 320 K, desorbed NO in quantum states with 25<ER<2162 cm−1 were represented by two distributions of molecules: a translationally energetic component with a mean kinetic energy 〈ET〉/2k which continuously increased from 1400 to 2650 K with increasing ER, a rotational temperature of TR=410 K, and a vibrational temperature of TV≈900 K; and a slower component with 〈ET〉/2k=300 K and TR=170 K.