Density matrix approach to photon-assisted tunneling in the transfer Hamiltonian formalism

Journal Article · 09 February 2018 · Physical Review B

DOI: https://doi.org/10.1103/PhysRevB.97.075411 · OSTI ID:1465798

Davids, Paul S. ^[1]; Shank, Joshua ^[1]

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1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

The transfer Hamiltonian tunneling current is derived in a time-dependent density matrix formulation and is used to examine photon-assisted tunneling. Bardeen's tunneling expression arises as the result of first-order perturbation theory in a mean-field expansion of the density matrix. Photon-assisted tunneling from confined electromagnetic fields in the forbidden tunnel barrier region occurs due to time-varying polarization and wave-function overlap in the gap which leads to a nonzero tunneling current in asymmetric device structures, even in an unbiased state. The photon energy is seen to act as an effective temperature-dependent bias in a uniform barrier asymmetric tunneling example problem. Higher-order terms in the density matrix expansion give rise to multiphoton enhanced tunneling currents that can be considered an extension of nonlinear optics where the nonlinear conductance plays a similar role as the nonlinear susceptibilities in the continuity equations.

• Research Organization: Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC04-94AL85000; NA0003525
• OSTI ID: 1465798
• Alternate ID(s): OSTI ID: 1420017
• Report Number(s): SAND-2017-11873J; PRBMDO; 663116; TRN: US1902559
• Journal Information: Physical Review B, Vol. 97, Issue 7; ISSN 2469-9950
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English