Gas Cluster Ion Beam Processing of GaSb and InSb Surfaces
- PDF / 478,040 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 21 Downloads / 245 Views
R10.7.1
Gas Cluster Ion Beam Processing of GaSb and InSb Surfaces K. Krishnaswami1, S.R. Vangala1, B. Krejca1, L.P. Allen2,3, C. Santeufemio3, H. Dauplaise4, X. Liu5, J. Whitten5, M. Ospina5, C. Sung5, D. Bliss4, and W.D Goodhue1 1. 2. 3. 4. 5.
Photonics Center, Dept. of Physics, University of Massachusetts, Lowell, MA 01854 Galaxy Compound Semiconductor, 9922 E. Montgomery #7, Spokane, WA 99206 Epion Corporation, 37 Manning Road, Billerica, MA 01821, USA Air Force Research Laboratory/SNHC, Hanscom AFB, MA 01731 Center for Advanced Materials, University of Massachusetts, Lowell, MA 01854
ABSTRACT Gas Cluster Ion Beam (GCIB) processing has recently emerged as a novel surface smoothing technique to improve the finish of chemical-mechanical polished (CMP) GaSb (100) and InSb (111) wafers. This technique is capable of improving the smoothness CMP surfaces and simultaneously producing a thin desorbable oxide layer for molecular beam epitaxial growth. By implementing recipes with specific gas mixtures, cluster energy sequences, and doses, an engineered oxide can be produced. Using GaSb wafers with a high quality CMP finish, we have demonstrated surface smoothing of GaSb by reducing the average roughness from 2.8 Å to l.7Å using a dual energy CF4/O2-GCIB process with a total charge fluence of 4x1015ions/cm2. For the first time, a GCIB grown oxide layer that is comprised of mostly gallium oxides which desorbed at 530ºC in our molecular beam epitaxy system is reported, after which GaSb/AlGaSb epilayers have been successfully grown. Using InSb, we successfully demonstrated substrate smoothing by reducing the average roughness from 2.5Å to 1.6Å using a triple energy O2-GCIB process with a charge fluence 9x1015ions/cm2. In order to further demonstrate the ability of GCIB to smooth InSb surfaces, sharp ~900 nm high tips have been formed on a poorly mechanically polished InSb (111)A wafer and subsequently reduced to a height of ~100 nm, an improvement by a factor of eight, using a triple energy SF6/O2-GCIB process with a total charge fluence of 6x1016ions/cm3. I.
Introduction
Antimonide-based compound semiconductors (ABCS) are promising candidates as “barrier materials” for optoelectronic and wireless devices that operate in the terahertz or midinfrared region from 8-14µm. ABCS material properties such as low effective electron/hole mass, high mobility, and low threshold voltage operation1 have led to the development of highquantum-efficiency photodetectors, thermo-photovoltaic devices, avalanche photodiodes, tunnel switch diodes, high-reflectivity Bragg reflectors for 1.5µm communications, and mid-to-infrared region quantum well laser diodes operating at room temperature. In order to fabricate such devices, it is necessary to have substrates that support epitaxial growth of ternary and quaternary materials that cover a wide spectral range. Amongst the ABCS family, GaSb is particularly well suited for this task owing to its lattice parameter of 0.609nm, which is between those of InAs and AlSb (0.606 and 0.614nm respectively)
Data Loading...
