We explore the possibility of using ternary Si1?x?yGexCy grown on Si as the material for detection of infrared light of wavelengths 1.3 µm and 1.55 µm. By using an empirical expression for the absorption coefficient , it is ensured that the ternary alloy exhibits values of as high as 5000 cm?1 at these wavelengths. From the corresponding values of the band gap, the compositions of the alloy are then ascertained by using an existing theory of band gap and band offset of ternary SiGeC alloy grown on (001) oriented Si. The estimated compositions are displayed as plots of x versus y (0.03) with different values of as parameters.
Spatial confinement of electrons in ultrathin layers of indirect gap Si, SiGe and SiGeC leads to a spread in the momentum of electrons, so that the envelope function of electrons possesses a sizeable Fourier component at k0, the wave vector for conduction band minima in the materials. Under this situation, the matrix elements for interband transition may be appreciably enhanced. In this work, the matrix elements for quasi-direct non phonon transitions have been evaluated for Si quantum wells, coupled Si/SiGe quantum wells and SiGeC/Si quantum wells. The absorption coefficient, (alpha) , for all these cases, are then calculated to examine the potential of the structures as emitters. The values of (alpha) are enhanced in quantum wells; however to achieve values of (alpha) , as large as in direct gap GaAs, quantum dots need be considered.
There is a need to develop reliable, low cost and efficient semiconductor sources at mid and far IR. The sources at mid- IR using II-VI and Iv-Vi compounds suffer from some limitations. There are proposals to develop THz emitters using novel concepts, but their practical realization is not imminent at present. Quantum Cascade Lasers based on intersubband transitions in coupled Quantum Wells and Superlattices have recently been the subject of intensive research. In this paper the basic mechanisms of these lasers using III-V compound based type I and II structures are mentioned and some recent results are mentioned. The possibility of obtaining population inversion in Si based QWs is then explored. The calculated values of transparency current density and gain in coupled triple QW structures using Si and SiGe are reported.
The proposed development of fibre-optic communication links at bit rates exceeding 10Gb/s places a demand for photoreceiveis with high bandwidth (BW). Metal-Semiconductor-Metal (MSM) photodetectors (PDs) show very high intrinsic bandwidth (500GHz), are easily integrable with High Electron Mobility Transistors (HEMTs) and HeteroBipolar Transistors (HBTs) and are very attractive for communication and chip-to-chip interconnections. Widespread interest is being shown to these photoreceivers and to optimize their performance. In this paper we have calculated the gain, BW and minimum detectable optical power of a combination of MSM-PD and a HEMT and of a MSM-PD and a HBT and made a comparison. The InGaAs-InP heterojunctions and quantum wells are in the heart of file devices. The intrinsic capacitance of MSM-PD is made very low (6fF). The HEMT or HBT is used in common source (emitter) and cascode configurations. The minimum detectable power is calculated for direct intensity modulation with NRZ coding. Typical values ofPmin for MSM-PD and HEMT combination are -35dBm for 0. 1Gb/s, -30dBm for lGb/s and - 25dBm for 10 Gb/s. Due to less gate current noise this combination gives a better performance than a MSM-PD and HBT combination. However, with inclusion of proper model of gate current noise, there is some degradation of performance. Some possible means to optimize the performance are discussed in this paper.
In strained Si Ge i-x/Si quantum wells alloy-disorder and intervalley phonon scatterings are found to be weak. The calculated values of mobility are higher than in bulk silicon and closer to the recent experimental data and are mainly limited by deformation potential acoustic phonon scattering. I .
Some basic optical processes in quantum well structures are described and some photonic devices utilizing the processes are discussed. The operation of the devices depend on the interaction between particles and the scatterers. The scattering mechanisms are mentioned and the role of the processes on absorption, lifetime, line width of emission and mobility are indicated.
We have calculated the mobility of 1s-excitons confined in a GaAs/AlGaAs quantum well limited by different scattering mechanisms over a temperature range from 10 K to 150 K for different well-widths.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.