First-principles predictions of band alignment in strained Si/Si1-xGex and Ge/Si1-xGex heterostructures

• URL: http://arxiv.org/abs/2603.13219v1
• Date: Fri, 13 Mar 2026 17:55:48 GMT
• Title: First-principles predictions of band alignment in strained Si/Si1-xGex and Ge/Si1-xGex heterostructures
• Abstract summary: Accurate band offsets are essential for predictive continuum modeling of nanostructures such as quantum wells and quantum dots formed in strained Si/Si1-xGex and Ge/Si1-xGex heterostructures.<n>We use atomistic first-principles density functional theory to compute valence- and conduction-band offsets across the full range 0 = x = 1.<n>The resulting offsets show pronounced composition nonlinearity beyond the linear models explored in previous works, agree with experimental benchmarks, and reproduce the high-Ge slope change in the relaxed-alloy band gap.
• Score: 5.681372142069633
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Accurate band offsets are essential for predictive continuum modeling of nanostructures such as quantum wells and quantum dots formed in strained Si/Si1-xGex and Ge/Si1-xGex heterostructures. Experimental offset data for these systems remain sparse away from endpoint compositions, making composition-dependent design difficult. We use atomistic first-principles density functional theory to compute valence- and conduction-band offsets across the full range 0 <= x <= 1. Random alloying is treated with special quasirandom structures, interface lineup terms are extracted from macroscopically averaged local Kohn-Sham potentials in thick periodic superlattices, valence-band spin-orbit coupling is included through species-resolved Mulliken weights, and conduction-band edges are refined using the screened hybrid Heyd-Scuseria-Ernzerhof functional. The resulting offsets show pronounced composition nonlinearity beyond the linear models explored in previous works, agree with experimental benchmarks, and reproduce the high-Ge slope change in the relaxed-alloy band gap. Analytic fitting expressions are provided for direct use in simulations, facilitating practical design of modern quantum technology devices.

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