Mechanical Properties and Crystal Growth Studies of Semiconductor Alloys

摘要

Compound semiconductors are attractive materials for optoelectronic devices sincethey present a broad selection of band gaps. The mechanical properties of these materials is of interest for both practical and theoretical reasons, however, there is a paucity of experimental information on this topic . The objective of this research program was to develop methods for providing reliable experimental information on the mechanical properties of compound semiconductors and their alloys. The main activity has been the measurement of the hardness of these materials. We have used two basic hardness measurements: conventional microhardness measurements, such as the Vickers hardness test; and the Nanoindentor hardness. For the former measurements, bulk crystals or thick films were needed. A significant part of the program was devoted to preparing relevant samples for these measurements. We used conventional methods of crystal growth for producing bulk crystals and we developed novel methods of vapor phase epitaxial growth to prepare thick films of variable composition. The Nanoindentor was used for measuring the hardness and the modulus of thin films and bulk samples were measured by Vickers or with the Nanoindentor. We investigated a wide variety of semiconductor systems for measurement, but we selected a few systems that had well established device applications for particular emphasis in our studies.