Controlling the growth morphology and phase segregation of Mn-doped Ga{sub 2}Se{sub 3} on Si(001).
- 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 Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- National Science Foundation (NSF); IBM Corp.
- DOE Contract Number:
- DE-AC02-06CH11357
- OSTI ID:
- 1018897
- Report Number(s):
- ANL/XSD/JA-68309; TRN: US201114%%402
- Journal Information:
- Phys. Rev. B, Vol. 83, Issue 15 ; Apr. 18, 2011
- Country of Publication:
- United States
- Language:
- ENGLISH
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