Band-Structure Engineering of P-Doped Ge/SiGe Heterostructures for Mid-infrared Photonic Devices

Abstract

This work presents a systematic theoretical investigation and band-structure engineering of p-doped Ge/Si_1−xGe_x multiple quantum wells (MQWs) tailored for mid-infrared (MIR) photonics. Using a self-consistent 6-band k·p Poisson-Schrödinger approach, we establish a predictive simulation framework that rigorously accounts for quantum confinement, epitaxial strain, and many-body interactions. A key feature of our model is the integration of realistic graded interfacial profiles and self-consistent many-body corrections—specifically local density approximation exchange—correlation and depolarization shifts. We demonstrate that these corrections are essential to resolve the observed 8–12 meV energy blueshift in high-density hole gases (> 10¹⁸cm⁻³), where standard single-particle approximations fail. By systematically optimizing well geometry, doping profiles, and Ge concentration, we achieve precise spectral tunability across the strategic 6–15 μm atmospheric window. Furthermore, our transport and optical models capture the complex valence band mixing between heavy, light, and split-off hole states, providing deep insights into intersubband absorption dynamics. The model's high predictive accuracy (> 95% compared to experimental MIR absorption spectra) establishes it as an indispensable tool for the ab-initio design of CMOS-compatible MIR emitters, quantum cascade lasers, and photodetectors. Ultimately, this framework bridges the gap between fundamental valence band physics and practical device performance, accelerating the development of next-generation monolithic silicon-photonics platforms.

Received: 13 January 2026 | Revised: 14 April 2026 | Accepted: 22 June 2026

Conflicts of Interest

The author declares that she has no conflicts of interest to this work.

Data Availability Statement

Data supporting the findings of this study are available from the corresponding author upon reasonable request.

Author Contribution Statement

Vittoria Urso: Conceptualization, Methodology, Software, Validation, Formal analysis, Investigation, Resources, Data curation, Writing – original draft, Writing – review & editing, Visualization, Supervision, Project administration.