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Session Q14 - DCMP: SEMICONDUCTORS: MAGNETISM
Mixed session, Friday morning, March 24, 8:00
Room J4, San Jose Convention Center
We have studied the structural and magnetic properties of GaAs semiconductors implanted with Mn at various doses (from 1\times 10^13 to 5\times10^16 ions/ cm^2 ). Implanted samples were subsequently annealed to relax the lattice damage. For high concentration, e.g. 1\times 10^16 / cm^2 , TEM studies reveal that the surface layer of the GaAs is heavily damaged and crystalline precipitates are formed upon rapid thermal annealing. The dimension of these precipitates is \sim 50-100 nm, and the inter-particle spacing is \sim 1 \mu m. These precipitates are identified as Mn and Ga rich crystalline phases using electron microdiffraction and energy dispersive X-ray analysis techniques. Low-temperature photoluminescence is measured on annealed samples of different doses in applied magnetic fields. The Mn band-acceptor peak is observed at 1.41 eV and only found in low dose samples. The data indicate carrier polarization as large as 60 % in 8T at this energy. The magneto-optic and magnetization results will be presented and the magnetic properties of the precipitates will be discussed.\par\bigskip\noindent *Supported by NSF MRL DMR-9123048 and STC for Quantized Electronic Structures DMR 91-20007, and AFOSR F49620-93-1-0177.