Integrated emitters with CMOS-compatible tuning for large scale quantum SiN photonic circuits

TL;DR

The paper tackles the challenge of scalable, low-loss quantum photonic integration by heterogeneously integrating InGaAs quantum dots embedded in GaAs nanobeams onto a CMOS-friendly SiN interposer using micro-transfer printing. The emitters reside in a p-i-n diode structure that enables Stark tuning and charge-noise suppression, preserving high purity and coherent emission. Key results include a printing yield of $94.7\%$, GaAs-SiN coupling of $82.2\%$, an exciton lifetime of $514\ \mathrm{ps}$, and a corrected single-photon purity of $g^{(2)}(0)=0.0572$ with minimal blinking ($<2.75\%$), tunable over about $1\ \mathrm{nm}$ with bias below $0.6\ \mathrm{V}$. Together, these findings demonstrate a scalable pathway toward co-integrating diverse quantum photonic components on a single, low-loss interposer chip, advancing practical quantum information processing architectures with CMOS-compatible control.

Abstract

Next-generation scalable quantum photonic technologies operating at the single photon level rely on bringing together optimized quantum building blocks with minimal optical coupling losses. Achieving this necessitates the heterogeneous integration of different elements onto a single interposer chip. Integrated quantum emitters are key enablers for generating single photons, inducing quantum nonlinearities, and producing entanglement. In this work, we demonstrate the scalable integration of mature InGaAs quantum dots embedded in GaAs waveguides onto a low-loss SiN photonic platform, as evidenced by a high processing yield of 94.7% using a commercially available micro-transfer printing tool. These integrated emitters are embedded within a p-i-n heterostructure that allows for noise suppression, near-blinking-free operation and wavelength tunability upon CMOS-level electrical biasing. With this, we pave the way for scalable integration of diverse quantum photonic devices on a single chip.

Figures (5)

• Figure 1: SiN/GaAs platform for quantum photonics a) Schematic of a micro-transfer printed GaAs nanobeam waveguide with diffraction grating coupler and tapered mode coupler to transmit light to the underlying SiN circuit. The pump laser beam used for top-excitation as well as the emitted single photons are indicated. b) Material layer stack of the printed coupon and SiN target. The metal layers on the p- and n-contacts are Cr/Au and Ni/Ge/Au stacks respectively while the final metallization on the SiN target as seen in part (a) of the figure is Ti/Au. Side tethers of the GaAs nanobeam for electrical biasing are not shown in this cross section. c) Microscope image of the same device from (a) after fabrication.
• Figure 2: Fabrication process for heterogeneous integration a) Fabrication steps from predefinition on the GaAs source sample to micro-transfer printing and metallization on top of the target SiN sample. b) Microscope image of the GaAs devices predefined on the source sample c) 3D schematic cross section of the released coupon d) Microscope image of released coupons e) Printed coupons on the SiN interposer f-h) 3D impression from microscope images of a sample containing (f) released coupons ready for picking up, (g) printed coupons on the SiN interposer and (h) complete devices after photoresist removal and final metallization.
• Figure 3: Assessment of micro-printing printing misalignment a) Scanning electron miroscope (SEM) image showing the GaAs nanobeam printed on top of the SiN target, indicating the lateral and possible rotational misalignment b) Contour plot of the simulation results for mode coupler transmission, performed with the eigenmode expansion method. 14 devices are experimentally characterized and their offsets are indicated with red crosses.
• Figure 4: Quantum emitter properties of the heterogeneously integrated device a) IV curves of different columns of micro-transfer printed coupons. In addition to devices being contacted in parallel, columns 1 and 2 are also interconnected to each other. Relatively high currents are measured above 0.6 V b) Second order correlation function at short and long (inset) timescales. The horizontal yellow line indicates the average peak amplitude c) Lifetime measurement and single-exponential fit of the same emission line d) Photoluminescence spectrum as a function of bias voltage. The transitions are tuned in wavelength due to the quantum confined Stark effect e) Spectrometer counts as a function of pump power, fitted with an indicated power function.
• Figure 5: Relative area of side peaks from the correlation function at long positive time delays, showing low levels of emitter blinking.