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Saroj Kanta Patra

Publications and source records attributed to Saroj Kanta Patra.

4 recordsLinked to original sources

GaAs nano-ridge laser diodes fully fabricated in a 300 mm CMOS pilot line

Silicon photonics is a rapidly developing technology that promises to revolutionize the way we communicate, compute, and sense the world. However, the lack of highly scalable, native CMOS-integrated light sources is one of the main factors hampering its widespread adoption. Despite significant progress in hybrid and heterogeneous integration of III-V light sources on silicon, monolithic integration by direct epitaxial growth of III-V materials remains the pinnacle in realizing cost-effective on-chip light sources. Here, we report the first electrically driven GaAs-based multi-quantum-well laser diodes fully fabricated on 300 mm Si wafers in a CMOS pilot manufacturing line. GaAs nano-ridge waveguides with embedded p-i-n diodes, InGaAs quantum wells and InGaP passivation layers are grown with high quality at wafer scale, leveraging selective-area epitaxy with aspect-ratio trapping. After III-V facet patterning and standard CMOS contact metallization, room-temperature continuous-wave lasing is demonstrated at wavelengths around 1020 nm in more than three hundred devices across a wafer, with threshold currents as low as 5 mA, output powers beyond 1 mW, laser linewidths down to 46 MHz, and laser operation up to 55 °C. These results illustrate the potential of the III-V/Si nano-ridge engineering concept for the monolithic integration of laser diodes in a Si photonics platform, enabling future cost-sensitive high-volume applications in optical sensing, interconnects and beyond.

physics.optics↗

Indium gallium nitride quantum dots: Consequence of random alloy fluctuations for polarization entangled photon emission

We analyze the potential of the $c$-plane InGaN/GaN quantum dots for polarization entangled photon emission by means of an atomistic many-body framework. Special attention is paid to the impact of random alloy fluctuations on the excitonic fine structure and the excitonic binding energy. Our calculations show that $c$-plane InGaN/GaN quantum dots are ideal candidates for high temperature entangled photon emission as long as the underlying $C_{3v}$-symmetry is preserved. However, when assuming random alloy fluctuations in the dot, our atomistic calculations reveal that while the large excitonic binding energies are only slightly affected, the $C_{3v}$ symmetry is basically lost due to the alloy fluctuations. We find that this loss in symmetry significantly impacts the excitonic fine structure. The observed changes in fine structure and the accompanied light polarization characteristics have a detrimental effect for polarization entangled photon pair emission via the biexciton-exciton cascade. Here, we also discuss possible alternative schemes that benefit from the large excitonic binding energies, to enable non-classical light emission from $c$-plane InGaN/GaN quantum dots at elevated temperatures.

cond-mat.mes-hall↗

Impact of second-order piezoelectricity on electronic and optical properties of $c$-plane In$_{x}$Ga$_{1-x}$N quantum dots: Consequences for long wavelength emitters

In this work we present a detailed analysis of the second-order piezoelectric effect in $c$-plane In$_{x}$Ga$_{1-x}$N/GaN quantum dots and its consequences for electronic and optical properties of these systems. Special attention is paid to the impact of increasing In content $x$ on the results. We find that in general the second-order piezoelectric effect leads to an increase of the electrostatic built-in field. Furthermore, our results show that for an In content $\geq$30\% this increase in the built-in field has a significant effect on the emission wavelength and the radiative lifetimes. For instance, at 40\% In, the radiative lifetime is more than doubled when taking second-order piezoelectricity into account. Overall our calculations reveal that when designing and describing the electronic and optical properties of $c$-plane In$_{x}$Ga$_{1-x}$N/GaN quantum dot based light emitters with high In contents, second-order piezoelectric effects cannot be neglected.

cond-mat.mes-hall↗

Experimental and theoretical analyses of strongly polarized photon emission from non-polar InGaN quantum dots

We present a comprehensive investigation of the polarization properties of non-polar a-plane InGaN quantum dots (QDs) and their origin with statistically significant experimental data and rigorous k.p modelling. The unbiased selection and study of 180 individual QDs allow us to compute an average polarization degree of 0.90, with a standard deviation of only 0.08. When coupled with theoretical insights, we show that a-plane InGaN QDs are highly insensitive to size differences, shape anisotropies, and indium content fluctuations. Furthermore, 91% of the studied QDs exhibit a polarization axis along the crystal [1-100] axis, with the other 9% polarized orthogonal to this direction. When coupled with their ability to emit single-photons, a-plane QDs are good candidates for the generation of linearly polarized single-photons, a feature attractive for quantum cryptography protocols.

cond-mat.mes-hall↗