Staircase band gap Si1−xGex/Si photodetectors

Abstract

We fabricated Si1−xGex/Si photodetectors by using a staircase band gap Si1−xGex/Si structure. These devices exhibit a high optical response with a peak responsive wavelength at 0.96 μm and a responsivity of 27.8 A/W at −5 V bias. Excellent electrical characteristics evidenced by good diode rectification are also demonstrated. The dark current density is 0.1 pA/μm2 at −2 V bias, and the breakdown voltage is −27 V. The high response is explained as the result of a staircase band gap by theoretical analysis.

Modelling of the Quantum Transport in Strained Si/SiGe/Si Superlattices Based P-i-n Infrared Photodetectors for 1.3 - 1.55 μm Optical Communication

“…This limitation prevents the use of strained SiGe materials for photodetector applications operating at normal incidence since a sufficiently large absorption depth is required to achieve appreciable quantum efficiency. Although Si/Si 0.4 Ge 0.6 /Si multiple-quantum wells (MQWs) strained layers have been demonstrated in electro-optical modulators involving interband transitions for normal incidence operation [7], so far only waveguide structures with laterally-injected light have been reported for photodetectors thanks to their enhanced light absorb-ing length [8]. Therefore, a larger Ge content is necessary to generate sufficient optical absorption at 1.3 or 1.5 µm wavelengths.…”

Metastable Ge1–xCx Alloy Nanowires

“…Group IV alloy semiconductors have been studied with great interest because of their potential applications in electronic and optoelectronic devices compatible with silicon (Si)-based technology. − Carbon-containing alloys such as Ge 1– x C x or Si 1– x C x are of particular scientific and technological interest because strain and band gap can be flexibly controlled by substitutional carbon incorporation into the group IV element matrix. − In spite of these promising properties, the growth of single crystalline alloy materials is very difficult due to the extremely low equilibrium solubility of carbon in bulk silicon (1 × 10 17 cm –3 ) and germanium (1 × 10 8 cm –3 ) . Nonequilibrium methods such as molecular beam epitaxy (MBE) or rapid thermal chemical vapor deposition (RTCVD) have therefore been used for carbon incorporation above the equilibrium value in bulk alloy systems. − Compared with bulk materials, the high-quality alloy materials can be synthesized more easily in nanoscale growth systems and several papers have reported incorporation of external atoms with low solubility into IV group semiconductor nanostructures using nonequilibrium growth mode. − …”

Composition Controlled Synthesis and Raman Analysis of Ge-Rich SixGe1–x Nanowires

“…Because of the direct bandgap, SiGe alloys find extensive use in integrated optoelectronics, thermoelectric energy conversion devices, heterojunction bipolar transistor devices and photo detector applications. [1][2][3] In this regard, the synthesis and understanding of fundamental behavior of SiGe alloy nanowires is of immense interest for nanoscale device fabrication. Carrier confinement in nanoscale SiGe alloys is expected to enhance the material properties of bulk SiGe alloys.…”