Free carrier modulation of a sub-bandgap CW laser beam: A Si optoelectronic chopper

In this work we introduced two beam photocarrier cross-modulation for creation of an optically driven photonic laser beam modulator using a semiconductor wafer as the active medium. Unlike other laser beam modulators, the process of modulation of an unmodulated sub-bandgap laser beam was made possible by generating a spatially- and free-carrier density-wave-dependent infrared absorption coefficient in the bulk of the semiconductor, following absorption of a collinear super-bandgap modulated laser beam. The experimental results showed that the modulation efficiency strongly depends on the transport parameters of the semiconductor material and on the power of the super-bandgap laser beam

Investigation of H

Single beam laser-induced infrared photocarrier radiometry (PCR) has been applied for measuring transport properties of H+ ion-implanted silicon samples. The contrast between the PCR signals inside and outside the area of implantation was investigated for different doses and energies of implantation. The H+ ion-implantation range of doses and energies was 3×1014 cm-2 - 3×1016 cm-2 and 0.75 MeV–2 MeV, respectively. Furthermore, a two-beam cross-modulation PCR technique was introduced to perform the same type of measurements inside and outside the implanted area. Comparison between contrasts from single- and double-beam methods showed significantly higher degree of sensitivity for the two-beam PCR technique

On the non-linear dependence of photocarrier radiometry signals from Si wafers on the intensity of the laser beam

The subject of this research was the dependence of the infrared photocarrier radiometric (PCR) signal on the intensity of the exciting super-bandgap laser beam. It has been shown that the amplitude of the PCR signal is proportional to the intensity to a power β, such that 1≤β≤2. The power dependence of the amplitude is an important indicator of the photoexcited carrier recombination physics, specifically in semiconductors ranging between monopolar (β = 1) and bipolar (β = 2) limits. The study was made with laser beams of varying power and spotsize and wafers with different transport parameters. It has been found that the conventional approach using β = 1 is inadequate and inconsistent with experimental slopes of amplitude vs. power

Photocarrier radiometric characterization of electronic transport properties of H

Industrial n-type Si wafers were H+-ion-implanted and the electronic transport properties were studied using photo-carrier radiometry (PCR). A fitting procedure was introduced using a relatively simple 2-layer PCR model in lieu of the more realistic but substantially more complicated 3-layer model. It was found that the 2-layer model provides an optimal tool for characterizing H+ ion implants, balancing accuracy, complexity and validity as compared to the simpler, but inaccurate, 1-layer model

Photocarrier radiometry of ion implanted semiconductors

The dependence of the photocarrier radiometric (PCR) signal on ion implant dose in Si is reported. The results show almost entirely monotonic behavior over a large range of industrially relevant fluences (1x10$^{10}$ to 1x10$^{16}$ cm$^{-2}$) for B$^+$, As$^+$, P$^+$, and BF2$^+$ implanted in Si wafers at various energies. In addition, increasing the absorption coefficient of the excitation source is shown to improve the sensitivity of the PCR amplitude to dose. A three-dimensional three-layer model is used to provide a quantitative understanding of the PCR response of ion-implanted semiconductors. Good agreement between theoretically calculated PCR signal dependence on dose and experimental results is obtained