Semiconductor Terahertz Technology
Abstract
During this contract, we have investigated the THz laser source based on group-IV elements and their alloys that can be developed on Si substrates. The design work focused on the structure of the so-called quantum cascade laser (QCL). Specifically, we designed a Ge/Ge0.076Si0.19Sn0.05 QCL using intersubband transitions at L-valleys of the conduction band which has a "clean" offset of 150meV situated below other energy valleys (Gamma, Chi). The entire structure is strain free because the lattice-matched Ge and Geo.76Si0.19Sn0.05 layers are to be grown on a relaxed Ge buffer layer on a Si substrate. Longer lifetimes due to the weaker scattering of nonpolar optical phonons reduce threshold current and potentially lead to room temperature operation. For the work on phonon waveguides, we have studied the characteristics of waveguides using interface phonon polaritons to confine far-infrared radiation within a sub-wavelength semiconductor layer. We have identified spectral operating regions within the Restrahlen band of a cladding layer that offers advantages over both traditional dielectric and metal clad waveguides. We showed that proposed waveguides can be used for far infrared low-threshold QCLs. The report is divided into two parts, one for the design of group-IV QCLs and the other for the phononic waveguides.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 15, 2009
- Accession Number
- ADA506386
Entities
People
- Greg Sun
Organizations
- University of Massachusetts Boston