THz intersubband electroluminescence from n-type Ge/SiGe quantum cascade structures

Abstract

We report electroluminescence originating from L-valley transitions in n-type Ge/Si${}_{0.15}$Ge${}_{0.85}$ quantum cascade structures centered at 3.4 and 4.9 THz with a line broadening of $\Delta f/f\approx 0.2$. Three strain-compensated heterostructures, grown on a Si substrate by ultrahigh vacuum chemical vapor deposition, have been investigated. The design is based on a single quantum well active region employing a vertical optical transition and the observed spectral features are well described by non-equilibrium Green's function calculations. The presence of two peaks highlights a suboptimal injection in the upper state of the radiative transition. Comparison of the electroluminescence spectra with similar GaAs/AlGaAs structure yields one order of magnitude lower emission efficiency.

References in corpus (7)

• Thermoelectrically cooled THz quantum cascade laser operating up to 210 K
• Electron transport in quantum wire superlattices
• Room temperature operation of n-type Ge/SiGe terahertz quantum cascade lasers predicted by non-equilibrium Green's functions
• Contrasting influence of charged impurities on transport and gain in terahertz quantum cascade lasers
• Atomic-scale insights into semiconductor heterostructures: from experimental three-dimensional analysis of the interface to a generalized theory of interface roughness scattering
• Material configurations for n-type silicon-based terahertz quantum cascade lasers
• Intersubband transition engineering in the conduction band of asymmetric coupled Ge/SiGe quantum wells

Cited by in corpus (1)

• 500-period epitaxial Ge/Si0.18Ge0.82 multi-quantum wells on silicon