Mingwei Li

Effects of annealing processing on morphological, compositional and Schottky characterization of PtSi/Si diodes

The surface structure of PtSi/Si thin films by pulsed laser deposition (PLD) was studied using atomic force microscopy (AFM). The compositional structure of the PtSi as determined from X-ray photoelectron spectroscopy (XPS) is discussed. A possible growth model is presented on studying the variation of morphological features (i.e., roughness and size of crystallites) with annealing temperature and film thickness. By the AFM studies and Schottky characterization measurements of PtSi formation during various annealing processing, suitable preparation conditions are proposed to form the continuous and smooth PtSi thin film on Si substrate with the favorable Schottky property by PLD.

Reducing the effective barrier height of a PtSi Schottky diode by a p+ doping spike using pulsed laser doping

The structure of PtSi/p + /p-Si fabricated by chemical vapour doping has been investigated for reduction of the Schottky barrier height. The interface structure and photoelectric properties of PtSi/p + /p-Si thin film structure have been studied. The results from AES profile analysis show that doped boron moves with the PtSi/Si interface during silicide growth. Concomitantly, the boron at the PtSi/Si interface out-diffuses to the Pt–PtSi interface. Finally, the boron piles up at the surface. It has been considered that the redistribution of the dopant boron is due to the solubility of the dopant in the silicide. The Schottky barrier height of PtSi/p + /p-Si is 0.13 eV (for cutoff wavelength 9.5 µm). That is lower than the 0.19 eV value of PtSi/p-Si (for cutoff wavelength 6.5 µm). Since the Schottky barrier height is lowered, the cutoff wavelength can be extended. Due to the Fowler dependence, the detector’s quantum efficiency can be improved.

Dynamic response of metal honeycomb sandwich structure under high-speed impact

The ARMOR TPS is one of important candidate structure of RLV. It will be the best selection for all kinds of RLV. So the ARMOR thermal protection system will be used in aviation and spaceflight field more and more widely. ARMOR TPS panel is above the whole ARMOR TPS, and the metal honeycomb sandwich structure is the surface of the ARMOR TPS panel. So the metal honeycomb sandwich structure plays an important role in the ARMOR TPS, while it bears the flight dynamic pressure and stands against the flight dynamic calefaction and impact load. The metal honeycomb sandwich structure is made of upper faceplate, lower faceplate and honeycomb core. In the course of the reusable launch vehicle working, it is possible that the space chips impact its outer surface. The main problem is what impact the metal honeycomb sandwich structure can stand and how many times it can stand. In the high speed impact experiment we choose different quality and velocity to simulate real space environment. This paper will analyze the mechanics behaviour of metal honeycomb sandwich structure in the course of impact, and then we make sure the limit impact load and get the effect of impact flaw.