Interaction Between Different Wavelengths Laser And Semiconductor Material HgCdTe And Si

Laser-material interaction has been an interesting problem. In the latest several decades,as the repaid development of laser technology, it has been used in various aspects of natural science,and greatly accelerated the research progress. In the other hand the new phenomena and findings in the research process greatly promoted the development of laser technology. 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.HgCdTe and Si 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. Si microelectronics field are indispensable for semiconductor materials, commonly used in optical systems to do the filter, infrared window, as well as substrate material and substrate material. 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. Because the excimer laser wave length of the high photon energy, the war in the future of high-power excimer laser has been classified as probably one of the main laser weapons. Clearly, the study of a typical excimer laser HgCdTe and Si semiconductor material of the damage effect and mechanism of injury has a very important practical significance. So studying the laser ablation of HgCdTe and Si deeply is of great significance in understanding the interaction between laser and material as well as in military affairs.A 248nm excimer pulsed laser and 1064nm laser were used to irradiate the surface of HgCdTe and Si 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 Si. The surfaces of HgCdTe chips irradiated by 248 nm excimer laser are examined by an optical microscope and scanning electron microscope,which are much different from that when irradiated by infrared in-band light. It shows that the damage mechanism of the crystal irradiated by infrared band 1064nm light is photothermal effect, while that to the irradiation of ultraviolet band 248nm light is incorporates both photochemical and photothermal effect. At the same time, the periodic ripple phenomenon on HgCdTe surface induced by laser irradiation and their formation mechanism are discussed too. Through analysis the laser-driven sound theoretical model can give a better explanation for that than the optical model and the thermal conductivity wave model.In this work, the surfaces of HgCdTe and Si materials irradiated by 248 nm excimer laser are examined by an optical microscope and a scanning electron microscope. Through comparative analysis of the damage surfaces, it is found that the damage mechanism of the HgCdTe crystal is very different from that of the Si. HgCdTe materials irradiated area of the edge of the hole wall of vertical well, almost not observed because of the result of thermal effects; The irradiated area at the edge of Si material, non-vertical wall of hole, and the edge of a large number of splash material, laser material after the surface of the liquid Si sputtering phenomenon. laser shock induced stress resulted in HgCdTe materials irradiated area appeared in the bottom of the mechanical damage stripping; the cause of the Si substrate material a radiation zone crack; HgCdTe and Si at the surface of two materials have had a periodic structure of the surface . The former incorporates both photochemical and photothermal effect. However, the later is dominantly photothermal effect.A Optical Multi-channel Analyzer (OMAⅣ) 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. Spectra obtained with a diagnosis of HgCdTe laser plasma electron density and temperature, which changes with the delay time trends are similar, both with time delay in the rapid decline in first and then slowing down the rate of decline; at a low rate of pressure decay greater than the speed of high pressure.