Probing negative differential resistance in silicon with a P-I-N diode-integrated T center ensemble

TL;DR

This work demonstrates in-situ probing of nonlinear electrical dynamics inside a silicon PIN diode by embedding a silicon T-center ensemble and using transient optical spectroscopy. The authors observe a field- and temperature-dependent transition to self-sustained carrier oscillations, indicative of negative differential resistance, manifested in both photoluminescence and electroluminescence. Through DC-biased PL, pulsed EL, and phase-space mapping, they reveal a coherent, defect-mediated oscillatory regime that aligns with an impurity-trapping and impact-ionization framework. The findings provide fundamental insight into cryogenic silicon behavior, advance understanding of T centers for quantum-device performance, and open avenues for defect-based local quantum sensing of nonlinear electric fields in semiconductors.

Abstract

Solid-state defect quantum systems are exquisite probes of their local charge environment. Nonlinear dynamical electric fields in solids are challenging to characterize directly, conventionally limited to coarse macroscopic methods which fail to capture subtle effects in the material. Here, through transient optical spectroscopy on an embedded T center ensemble, we realize the in-situ observation of a silicon PIN-diode phase transition to a regime of self-sustained carrier oscillatory dynamics characteristic of negative differential resistance. Manifest in both the ensemble electroluminescence and photoluminescence, we find a temperature and field-dependent phase space for persistent undamped amplitude oscillations indicative of a collective ensemble response to the field dynamics. These findings shed new light on the cryogenic behavior of silicon, provide fundamental insight into the physics of the T center for improved quantum device performance, and open a promising new direction for defect-based local quantum sensing in semiconductor devices.

Figures (4)

• Figure 1: DC-bias induced electrical phase transition coupled to emission of telecom photons from silicon artificial atoms(a.) The T center is a carbon-related defect in silicon which emits photons in the telecommunication-band and possesses an addressable ground-state spin. An ensemble of T centers is incorporated in a buried lateral P-I-N diode fabricated in silicon via lithography-defined ion doping. Arrow indicates T center electroluminescence (EL) emission upon applied forward bias. MHz-frequency carrier oscillations are induced via application of a forward DC-bias which modulate the optical emission of an embedded T center ensemble. The oscillatory electrical dynamics are characteristic of a temperature- and field-dependent phase transition from the diode-ensemble interaction, observed when the impact ionization control parameter X crosses a critical point $I_c$scholl2012. (b.) Field-dependence of oscillatory T center ensemble photoluminescence (PL) at 6 Kelvin. (c.) IV curves of P-I-N diode with integrated T center ensemble. Reverse-bias reveals burst noise characteristic of defect trapping hsu1970, with multiple traces provided illustrating the random fluctuations.
• Figure 2: T center DC-bias optical response Intensity confocal scans and zero phonon line spectra of lithographically-defined T center ensemble confined to the I-region of a P-I-N diode measured via (a.) photoluminescence ($1~$mW, $532~$nm excitation), and (b.) electroluminescence ($9~$V, $\sim2~$mA). Relative PL vs EL intensity curves given in supplement SI.
• Figure 3: Transient oscillatory dynamics in DC-biased photoluminescence(a.) Pulse sequence for DC-biased pulsed photoluminescence. (b.) Pulsed PL+DC oscillations. Within the stable region (9V, 6 Kelvin), oscillations persist without damping. (c.) Mapping the oscillation instability as a function of temperature (left) and field (right) while holding constant the alternative control parameter.
• Figure 4: Phase space of oscillation stability(a.) Voltage dependence of transient EL oscillations observed in T center optical response (left) with FFT per voltage (right) (b.) Voltage dependence on transient diode current oscillations (left) with FFT per voltage (right). The T center emission is vertically offset for clarity, whereas the vertical rise in diode current is directly due to the increased applied voltage. (c.)-(d.) Phase map of oscillation strength as a function of voltage and temperature, revealing stable and absent phases of oscillations in the T center (c), and diode current (d). The oscillation strength $A/\gamma$ (where $A$ and $\gamma$ are the fourier transform amplitude and linewidth, respectively) at each voltage and temperature condition is measured by taking the fourier transform of the oscillation dynamics. A phase transition is observed in the traversal across the x- and y-axes of the phase diagrams, crossing a critical point of the impact ionization control parameter.