Controlling the growth morphology and phase segregation of Mn-doped Ga{sub 2}Se{sub 3} on Si(001).

Journal Article · Mon Apr 18 04:00:00 EDT 2011 · Phys. Rev. B

DOI:https://doi.org/10.1103/PhysRevB.83.155312· OSTI ID:1018897

Lovejoy, T C; Yitamben, E N; Heald, S M; Ohuchi, F S; Olmstead, M A ^[1]

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1. X-Ray Science Division

The growth and phase segregation properties of the potential dilute magnetic semiconductor alloy (MnSe){sub x}(Ga{sub 2/3}Se){sub 1-x} are studied as a function of thickness, Mn concentration, postgrowth annealing, and the presence or absence of undoped Ga{sub 2}Se{sub 3} buffer and capping layers. This system is an unusual case in heteroepitaxy where two-phase MnSe{sup +}Ga{sub 2}Se{sub 3} has better lattice matching than the (MnSe){sub x}(Ga{sub 2/3}Se){sub 1-x} alloy. Despite this peculiarity, this system shows a modified form of Stranski-Krastonow growth: laminar films are observed up to a certain x-dependent critical thickness, above which islands are observed by scanning tunneling microscopy. The island morphology depends on the presence or absence of an undoped Ga{sub 2}Se{sub 3} buffer layer and postgrowth annealing. A kinetically stabilized platelet morphology is observed at the crossover point between laminar and islanded films. Based on Mn and Se K-edge extended x-ray absorption fine structure and x-ray absorption near-edge structure spectroscopy, there are two types of Mn in islanded films: Mn that remains doped in the Ga{sub 2}Se{sub 3} but oxidizes upon exposure to air, and Mn that participates in the islands, which are precipitates of the MnSe phase. Consistent with MnO or MnSe, L-edge x-ray absorption on air-exposed films suggests the Mn is in the formal +2 oxidation state. No L-edge x-ray magnetic circular dichroism signal is observed at 20 K, which may be due to surface effects or to a lack of magnetic order.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: NSF; IBM Corp.
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 1018897
• Report Number(s): ANL/XSD/JA-68309
• Journal Information: Phys. Rev. B, Journal Name: Phys. Rev. B Journal Issue: 15 ; Apr. 18, 2011 Vol. 83; ISSN 1098-0121
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ABSORPTION
AIR
ALLOYS
ANNEALING
BUFFERS
FINE STRUCTURE
ISLANDS
MAGNETIC CIRCULAR DICHROISM
MAGNETIC SEMICONDUCTORS
MORPHOLOGY
SCANNING TUNNELING MICROSCOPY
SEGREGATION
SPECTROSCOPY
THICKNESS
VALENCE