Photoluminescence and photoconductivity of Si- and Ge-rich SiGe bulk crystals

Abstract

We have investigated Si-(0рxр0.13) and Ge-rich (0.90рxр1) Si 1Ϫx Ge x bulk crystals by photoluminescence and photoconductivity measurements. The small linewidths of the near band edge luminescence of less than 4 meV demonstrate the high quality of the crystals. Luminescence linewidth, line shape, and intensity ratios of transitions with and without phonon participation reveal a stronger influence of alloy effects on excitons on the Ge-rich side compared with the Si-rich side. Photoconductivity spectra of boron doped Si-rich and phosphorus doped Ge-rich Si 1Ϫx Ge x crystals show the influence of alloy composition and alloy fluctuations on the impurity levels. The shift of the photoconductivity spectra with increasing Si or Ge concentration indicates the change of the ground state energy of the impurity with changing alloy composition.

Electron heating in capacitively coupled discharges and reactive gases

“…Data are reported elsewhere. [14][15][16][17] Plasma analysis is carried out using electrical measurements ͑plasma impedance and other characteristic properties, Z sensor of Advanced Energy͒, optical measurements ͑opti-cal emission spectroscopy͒ with an optical multichannel analyzer system of EG & G, a monochromator ͑Jerrell-Ash Monospec 27͒ to evaluate the electron temperature T e in the high-energy tail of the EEDF, 1 a Langmuir probe from Technical University of Munich to measure conventionally defined T c and the electron plasma density n e along with the plasma potential V p , and a SEERS sensor ͑Hercules PL͒ from Advanced Semiconductor Instruments to measure the space averaged values for the electron plasma density n e and the effective collision frequency of electrons with neutrals eff being the sum of elastic collision and the stochastic heating rate. [18][19][20] Since measurements of the high-energy tail of the EEDF with optical emission spectroscopy require the application of at least two rare gases, normally Ar/ Kr or Ar/ Xe, 1 we also applied Ar/ Kr ͑1:1͒ in our experiments.…”

Size distribution and electroluminescence of self-assembled Ge dots

“…For the effective mass of holes for unstrained Si 1Ϫx Ge x we used the formula 34 m hh ϭ0.2907Ϫ0.09021x ϩ0.00552x 2 . Other parameters are: Band gap of Si at 125 K: 1153 meV, and band gap of relaxed Si 1Ϫx Ge x from Franz et al 35 The peak position is defined as the sum of band gap in the island and the confinement energy of holes for different Ge concentrations. The binding energy of excitons was neglected.…”

Analysis of chlorine-containing plasmas applied in III/V semiconductor processing

“…As we have shown elsewhere, 28 we can parametrize the Cl͑I͒ lines at 438.8 and 452.6 nm actinometrically using the flow of molecular chlorine, i.e., the partial pressure in the discharge, as variable. That means that the excitation to upper levels must be a one-step process starting from the parent molecule Cl 2 , in accordance with this plasma analysis.…”