Molecular Beam Epitaxy on Gas Cluster Ion Beam Prepared GaSb Substrates: Towards Improved Surfaces and Interfaces

Journal Article · Tue Apr 01 00:00:00 EDT 2008 · Journal of Crystal Growth, 310(7-9):1619-1626

DOI:https://doi.org/10.1016/j.jcrysgro.2007.11.225· OSTI ID:927704

Krishnaswami, Kannan; Shivashankar, Vangala; Dauplaise, Helen; Allen, Lisa; Dallas, Gordon; Bakken, Daniel; Bliss, David; Goodhue, William

A key problem in producing mid-infrared optoelectronic and low-power electronic devices in the GaSb material system is the lack of substrates with appropriate surfaces for epitaxial growth. Chemical mechanical polishing (CMP) of GaSb results in surface damage accompanied by tenacious oxides that do not easily desorb. To overcome this, we have developed a process using gas cluster ion beams (GCIB) to remove surface damage and produce engineered surface oxides. In this paper, we present surface modification results on GaSb substrates using O2-, CF4/O2-, and HBr-GCIB processes. X-ray photoelectron spectroscopy of GCIB produced surface layers showed the presence of mixed Ga- and Sb-oxides, with mostly Ga-oxides at the interface, desorbing at temperatures ranging 530°C to 560°C. Cross-sectional transmission electron microscopy of molecular beam epitaxy grown GaSb/AlGaSb layers showed that GCIB surfaces yielded smooth defect free substrate to epi transitions as compared to CMP surfaces. Furthermore, HBr-GCIB surfaces exhibited neither dislocation layers nor discernable interfaces, indicating complete oxide desorbtion prior to epigrowth on a clean single crystal template. Atomic force microscopy of GCIB epilayers exhibited smooth surfaces with characteristic step-terrace formations comprising monatomic steps and wide terraces. The HBr-GCIB process can be easily adapted to a large scale manufacturing process for epi-ready GaSb.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 927704
• Report Number(s): PNNL-SA-60073; JCRGAE; TRN: US200816%%1223
• Journal Information: Journal of Crystal Growth, 310(7-9):1619-1626, Vol. 310, Issue 7-9; ISSN 0022-0248
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ATOMIC FORCE MICROSCOPY
DEFECTS
DESORPTION
DISLOCATIONS
ION BEAMS
MANUFACTURING
MECHANICAL POLISHING
MODIFICATIONS
MOLECULAR BEAM EPITAXY
MONOCRYSTALS
OXIDES
SUBSTRATES
TRANSMISSION ELECTRON MICROSCOPY
X-RAY PHOTOELECTRON SPECTROSCOPY
Molecular beam epitaxy
gas cluster ion beam
GaSb
surface oxides