Interaction Between Laser And Semiconductor Material HgCdTe And GaAs

Laser-material interaction has been an interesting problem. Since the first laser was invented by T. H. Maiman, a physicist of USA, in 1960, laser technique has shown its vital force and has been introduced to almost every field of natural science. The achievement of the study of "laser-material interaction"is an important symbol of the development of laser technique. Laser-material interaction is one of the most important tasks of physics not only in theoretic fields but also in practical application such as laser processing, preparation of materials, manufacture of military weapons and so on. In recent years, the rapid development of the high energy ultrashort laser provide people with extreme experimental conditions such as unprecedented power density (>1020 W/cm2), field intensity (>1011 V/cm2) and time precision (10-15 s) etc which will lead to a lot of created study and breakthrough. HgCdTe and GaAs are both significant material in the infrared electronics field. HgCdTe has brought about great changes in developing photoelectric detectors. It has perfect performance and is regarded as the best infrared detecting material in the world. GaAs can be used as the preparation of quantum well infrared detector and it is competitive in the field of space infrared electronic technology. As a result of the above characters HgCdTe and GaAs are widely used in the military affairs. With the rapid development of new-style laser arms, all kinds of military detectors will face the threatening of laser arms. So studying the laser ablation of HgCdTe and GaAs deeply is of great significance in understanding the interaction between laser and material as well as in military affairs. In addition, it is difficult to produce both the material because of their complex preparation and high cost. In particular, the preparation of HgCdTe is regarded as the most defiant work in the world. Pulse Laser ablation Deposition (PLD) technique is a method of thin film preparation which was produced during the study of laser induced plasma. So it is important to decide the character of plasma which will influence the property of film most. In this paper, the plasma characters of interaction between pulsed laser and HgCdTe, GaAs material was studied and valuable conclusion could help to improve the PLD technology and the property of the film. A Nd:YAG pulsed laser was used to irradiate the surface of HgCdTe and GaAs in this experiment. And the ablated surface was detected with a SEM. We described the surface morphological changes in different laser power density, different pulse and different background pressure conditions. We also analyzed the two mechanisms of crack damages which included thermal stress crack and crack induced by vapor pressure and shock pressure. It could be concluded from our experiment that the sputtering phenomenon was more obvious with ten laser pulses and the distance of the sputtering increased with the decrease of the background pressure. The ablation threshold of HgCdTe was measured in our experiment and the result showed that the ablation threshold also increased with the decrease of the background pressure. In addition, acoustic wave theory was used to explain the surface period structure on the irradiated surface of HgCdTe and GaAs. In the present work, we improved the model of Anisimov-Krokhin by taking into account the heat of fusion of the irradiated material, the heat of the evolving liquid layer and the effective absorption of the laser. The dynamical parameters such as the pressure, the velocity, the temperature and the density of HgCdTe vapor were calculated using an iterative calculation process. And we got that the vapor pressure, density and the advanced velocity of the vapor wave increased linearly with the increase of laser power density while the vapor temperature and velocity increased logarithmically. Moreover, we calculated the pressure induced by vapor pressure and by shock wave with the dynamical parameters and consequently explained the crack we found in Chapter Two. A Optical Multi-channel Analyzer (OMAâ…¢) was applied to detect the emission of the plasma. The result showed that the plasma had been ignited within a very short time after the laser pulse reaching the surface and the plasma emission resulted in strong continuum. The continuum emission decreased as time went on and as the detector's location was away from the target. The temporal evolution process of the plasma emission could be divided into three stages namely continuum emission, ionic emission and atomic emission. In this paper, Monte-Carlo simulation program Trim98 was used to simulate the projected range of As+ which showed that the projected range of As+ increased with the decrease of the background pressure. We also got the time-of-flight (TOF) curves of Ga atom and explained the...