Modeling Photocurrent Spectra of In$_{0.91}$Ga$_{0.09}$N/In$_{0.4}$Ga$_{0.6}$N Disk-in-Wire Photodiode on Silicon for $1.3$ $\mu$m $-$ $1.55$ $\mu$m Operation

TL;DR

This paper presents a detailed theoretical model of photocurrent spectra in a specific InGaN disk-in-wire photodiode, incorporating strain, band structure, electrostatics, and tunneling effects, aligning well with experimental results.

Contribution

It introduces a comprehensive multi-physics modeling approach for photocurrent spectra in InGaN nanowire photodiodes, combining strain, band structure, electrostatics, and tunneling calculations.

Findings

Photocurrent spectra match experimental data.

Identified mechanisms behind prominent spectral peaks.

Demonstrated the importance of tunneling and optical cavity effects.

Abstract

This work reports comprehensive theoretical modeling of photocurrent spectra generated by an In$_{0.91}$Ga$_{0.09}$N/In$_{0.4}$Ga$_{0.6}$N disk-in-wire photodiode. The strain distribution is calculated by valence-force-field (VFF) model, while a realistic band structure of the InN/InGaN heterostructure is incorporated using an eight-band effective bond-orbital model (EBOM) with spin-orbit coupling neglected. The electrostatic potential is obtained from self-consistent calculation employing the non-equilibrium Green's function (NEGF) method. With the strain distribution and band profile determined, a multi-band transfer-matrix method (TMM) is used to calculate the tunneling coefficients of optically-pumped carriers in the absorbing region. The photocurrent spectra contributed by both single-photon absorption (SPA) and two-photon absorption (TPA) are calculated. The absorption coefficient is weighted by the carrier tunneling rate and the photon density-of-state (DOS) in the optical cavity formed in the nanowire region to produce the photocurrent. The calculated photocurrent spectra is in good agreement with experimental data, while physical mechanisms for the observed prominent peaks are identified and investigated.