Micromechanical Characterization of Gasb by Microbeam Deflecion and Using Nanoprobe and Finite Element Analysis

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A5.14.1

MICROMECHANICAL CHARACTERIZATION OF GaSb BY MICROBEAM DEFLECION AND USING NANOPROBE AND FINITE ELEMENT ANALYSIS M. Ospina1, S. R. Vangala2, D. Yang3, J. A. Sherwood4, C. Sung1, and W. D. Goodhue2 1

Center for Advanced Materials, University of Massachusetts, Lowell, MA 01854 Photonics Center, University of Massachusetts, Lowell, MA 01854 3 Hysitron, Inc., 10025Valley View Road, Minneapolis, MN 55439 4 Advanced Composite Materials Lab., University of Massachusetts, Lowell, MA 01854 2

ABSTRACT The commercial development of low-power electronics and electro-optics based on antimonides demands a better understanding of the mechanical properties of ternary and quaternary thin-film alloys fabricated from the InGaAlAsSbP material system. Of particular importance is the determination of Young’s modulus of these materials. In this paper, a technique for studying the mechanical behavior of these thin films was developed by using microbeam bending and finite element modeling. The technique was successfully applied to investigate the mechanical properties of GaSb. A test structure consisting of an array of gallium antimonide microbeams was fabricated with lengths ranging from 50 to 500 µm long. The microbeams were deflected using a calibrated nanoprobe, thereby generating load-displacement curves. Young’s modulus was then extracted from the data using beam bending theory and a finite element simulation of the structures under load. A total of five microbeams with the same trapezoidal cross-section and lengths of 80, 85, 200, 250 and 500 µm were tested to study the technique applicability and size scaling effects on the mechanical properties. It was observed that the 80 and 85 µm beams exhibited linear elastic behavior and the 200, 250, and 500 µm microbeams exhibited non-linear elastic behavior. I. INTRODUCTION This study is presented at this time due to new opportunities for III-V semiconductor materials. More specifically, the Antimonide based compound semiconductors (ABCS) material system in the semiconductor industry has recently been postulated as an alternative new family of semiconductor devices. A wide range of electronic bandgaps are possible with these materials. Gallium antimonide has been the focus of this study since it is a promising candidate for high-speed electronic and long-wavelength photonic devices. Gallium antimonide material properties have been mainly assessed by electrical and optical measurements providing sufficient information to understand the basic properties. More research has to be pursued regarding its implementation in commercial applications and devices. From the mechanical perspective, the accurate assessment of material properties in the sub-micron range is critical for the mechanical integrity of microstructures. II. FABRICATION OF GaSb TEST STRUCTURES The array of gallium antimonide microbeams was fabricated in three sequential steps: the deposition of photoresist layers by microlithography patterning and bromine ion-beamassisted etching (Br IBAE). The pattern layout used was a 1