Characterization of Erbium Doped SiO 2 Layers Formed On Silicon By Spark Processing
- PDF / 1,075,662 Bytes
- 6 Pages / 414.72 x 648 pts Page_size
- 52 Downloads / 172 Views
Mat. Res. Soc. Symp. Proc. Vol. 486 ©1998 Materials Research Society
Experimental Procedure SparkProcessedEr on Si :Formationand Characterization Square pieces (15 mm x 15 umm) of p-type, , boron doped CZ Si (6-8 fa cm) were used as substrates in these experiments. Metallic contact was made to the back of the wafers using Ni wire and Ag epoxy. Thin layers of Er(N0 3 )3 .5H 2 0 were deposited on the surfaces of silicon wafers by allowing a dilute solution of the salt to evaporate. The samples were coated by depositing 10 or 25 W1 of a solution with concentrations ranging from 0.01 M to 0.5 M Er(N0 3)3 .5H2 0 in water via syringe onto the wafer surface. Upon evaporation, circular layers of erbium salt crystals approximately 3 mm in diameter were left on the wafer surface. Spark processing was achieved by connecting the sample to the cathode of an Electro Technics Products Tesla coil providing a high-frequency (15 KHz), high-voltage (104 V), low current (several mA) spark. An untreated silicon wafer was used as the anode. The arc from the coil migrates across the silicon substrate, and the size of the spark processed region is a function of the spark gap. The gap was adjusted so that the entire layer of rare earth crystals was processed by the arc. Samples were processed in air for 60 minutes. After processing, samples were washed with de-ionized H2 0, ethanol and acetone, then dried under a stream of dry nitrogen. Low resolution near IR photoluminescence (PL) spectra were obtained using an Applied Detector Corp.-liquid N 2 cooled Ge detector in conjunction with a Stanford Research Systems Chopper/Lock in amplifier and an Acton Research Corp. 0.25 m monochromator. Excitation was provided by a Coherent argon-ion laser. High resolution near IR PL spectra and high resolution visible spectra were performed using the 488 nm line of a Coherent argon-ion laser. Fluorescence was focused on the slit of a Spex 1 m monochromator with a photomultiplier tube used to detect visible PL, and a liquid N 2 cooled Ge detector used for near IR PL measurements. Cooling for all PL measurements was achieved by mounting the sample in a closed cycle helium cryostat. Scanning Electron Microscopy (SEM) was performed using a JEOL T 300 operating at 20 kV. Energy dispersive x-ray spectroscopy (EDS) of the spark processed regions was used to obtain two EDS maps of the same area, one showing Si, and one showing Er. MCID software from Imaging Research Inc. was employed to measure the integrated Si nd Er EDS intensities from the EDS maps. Ratios of Er to Si were used to determine the density of Er3+ in the spark processed region for varying initial Er3 +salt concentrations. Erbium-dopedDensifiedPorousSi Formationand Characterization Samples were prepared by forming a thin layer of porous silicon on a 1.0 cm2 piece of ptype, , boron doped CZ Si (6-8 f0 cm). The porous layer was prepared by forming metallic contact to the back (rough) side of the wafers. The wafers were connected to the anode of a potentiostat and biased in a 1:1 solution of 48% HF:
Data Loading...
