SILICON OPTICAL RADIATION SOURCE (001)

Abstract

This utility model pertains to integrated photonics, specifically to stimulated emission devices. The technical result is improved energy efficiency of an optical radiation source on CMOS-compatible silicon wafers.An optical radiation source consisting of a semiconductor silicon substrate with the (001) orientation, profiled with V-shaped notches, onto which an oxide layer of SiO2 with windows in it is applied, and sequentially arranged epitaxially grown layers: a buffer layer made of GaAs, a lower barrier layer made of AlGaAs and a lower barrier layer made of GaAs; an active region consisting of pairs of GaAs layers containing InAs quantum dots; an upper barrier layer made of GaAs and an upper barrier layer made of AlGaAs, which, together with the lower barrier layers, are designed with the possibility of localizing charge carriers; an upper thin layer made of GaAs and serving to protect the underlying layers of the entire heterostructure; and a Fabry-Perot resonator for outputting directed radiation. 2 fig.

Description

[0001] The proposed utility model relates to the field of integrated photonics, and specifically to devices with stimulated emission.

[0002] An analogue of the claimed object is known - an optical radiation source [Si Zhu, Bei Shi, Qiang Li, Kei May Lau. 1.5 µm quantum-dot diode lasers directly grown on CMOS-standard (001) silicon / / Applied Physics Letters, 2018, 113, 221103], containing a semiconductor silicon substrate profiled with V-shaped notches, covered with buffer epitaxial layers, dislocation filters, on which there is an active region consisting of pairs of InAs / InAlGaAs layers.

[0003] This design of the optical radiation source can improve its energy efficiency.

[0004] The features of the analogue, which coincide with the essential features of the claimed object, are: a semiconductor silicon substrate profiled with V-shaped notches, buffer epitaxial layers, an active region containing quantum dots.

[0005] The reasons that prevent the achievement of the technical result are: the growth of thick buffer layers and numerous dislocation filters with a final structure thickness of ~7 μm, which leads to an insufficient reduction in the level of dislocation density, to an increase in the cost of the final structure and to the potential formation of thermal cracks associated with different temperature coefficients of the substrate and the grown structure, a high threshold current density, operation in a pulsed mode and poor temperature stability limit the practical application of such a laser in real photonic circuits where stable continuous radiation is required.

[0006] An analogue of the claimed object is known - a source of optical radiation [Ting Wang, Huiyun Liu, Andrew Lee, Francesca Pozzi, Alwyn Seeds. 1.3-μm InAs / GaAs quantum-dot lasers monolithically grown on Si substrates / / Optics Express, 2011, 19, 11381-11386], containing a semiconductor silicon substrate, buffer layers, epitaxial layers for filtering defects, barrier layers, between which there is an active region consisting of pairs of InAs / InGaAs layers.

[0007] This design of the optical radiation source can improve its energy efficiency.

[0008] The features of the analogue, coinciding with the essential features of the claimed object, are: a semiconductor silicon substrate, buffer layers, barrier layers, and an active region.

[0009] The reasons preventing the achievement of the technical result are: the growth of thick buffer layers and numerous dislocation filters with a final structure thickness of ~3.3 μm, which leads to an insufficient reduction in the level of dislocation density, to an increase in the cost of the final structure, to the potential formation of thermal cracks associated with different temperature coefficients of the substrate and the grown structure, the use of a misoriented substrate, which leads to the impossibility of integrating such a device with modern CMOS technology, a low maximum operating temperature, a relatively high threshold current density and operation in a pulsed mode limit the practical application of such a laser in real photonic circuits where stable continuous radiation is required.

[0010] Among the known ones, the closest in technical essence to the claimed object is the laser structure [Y. De Koninck, C. Caer, D. Yudistira, M. Baryshnikova, H. Sar, P.-Y. Hsieh, CI Özdemir, SK Patra, N. Kuznetsova, D. Colucci, A. Milenin, AA Yimam, G. Morthier, D. Van Thourhout, P. Verheyen, M. Pantouvaki, B. Kunert, J. Van Campenhout. GaAs nano-ridge laser diodes fully fabricated in a 300-mm CMOS pilot line / / Nature, 2025, 637, 63-69], containing a semiconductor silicon substrate with an oxide layer, profiled with V-shaped notches, covered with epitaxial buffer layers, on which is located the active region, consisting of layers of narrow-bandgap semiconductor separated by epitaxial layers (GaAs).

[0011] This design of the optical radiation source can improve its energy efficiency.

[0012] The features of the prototype, which coincide with the essential features of the claimed object, are: a semiconductor silicon substrate with an oxide layer, profiled with V-shaped notches, epitaxial layers (GaAs), an active region consisting of layers of a narrow-band semiconductor separated by epitaxial layers (GaAs).

[0013] The reasons preventing the achievement of the technical result are: nanocombs with quantum wells are strongly susceptible to the influence of threading dislocations, some of which still reach the upper layers of the final structure; the use of the method of deposition of metal-organic compounds from the gaseous phase, which leads to poor control of the thickness of the active region structures; the low maximum operating temperature limits the practical application of such a laser in real photonic circuits.

[0014] The technical result of the utility model is to improve the energy efficiency of an optical radiation source on CMOS-compatible silicon wafers.

[0015] The technical result is achieved due to the fact that in the optical radiation source, consisting of a semiconductor silicon substrate with the orientation (001), profiled with V-shaped recesses, on which an oxide layer of SiO2 with windows in it is applied and sequentially located epitaxially grown layers: a buffer layer made of GaAs, a lower barrier layer made of AlGaAs and a lower barrier layer made of GaAs; an active region consisting of pairs of GaAs layers containing InAs quantum dots; an upper barrier layer made of GaAs and an upper barrier layer made of AlGaAs, which together with the lower barrier layers are designed with the possibility of localizing charge carriers; an upper thin layer made of GaAs and serving to protect the underlying layers of the entire heterostructure; and a Fabry-Perot resonator for outputting directed radiation.

[0016] The general view of the optical radiation source is shown in Fig. 1 and 2, where 1 is a semiconductor silicon substrate of the (001) orientation with V-shaped notches, 2 is an oxide layer of SiO2 with windows in it, 3 is a buffer layer made of an epitaxial layer of GaAs, 4 is a lower barrier layer of AlGaAs, 5 is a lower barrier layer of GaAs, 6 is an active region based on pairs of GaAs layers containing InAs quantum dots, 7 is an upper barrier layer of GaAs, 8 is an upper barrier layer of AlGaAs, 9 is an upper thin layer of GaAs, 10 is a Fabry-Perot resonator.

[0017] The optical radiation source operates as follows.

[0018] An external laser beam with a pump photon energy greater than the band gap of the barrier layers is focused onto the active region of the structure through the top GaAs barrier layer 9. The use of a (001)-oriented semiconductor silicon substrate with V-shaped notches 1 reduces the dislocation density and improves the homogeneity of the InAs quantum dots in the active region 6, which increases the charge carrier lifetime, reduces the lasing threshold and internal optical losses, and simultaneously improves the energy efficiency of the optical radiation source. The SiO2 oxide layer with windows 2 prevents parasitic lasing in the regions outside the windows, lowering the pump threshold. The GaAs buffer layer 3 smooths the relief of the V-notches and further reduces the dislocation density. Pump photons pass through the top layers and are absorbed mainly in the GaAs barrier layers 5 and 7.Absorption creates electron-hole pairs, and free electrons and holes diffuse across GaAs layers 5 and 7. When they enter the active region of InAs quantum dots 6, they are effectively captured. The trapped electron and hole recombine, emitting a photon with a wavelength in the near-IR range. The structure formed by AlGaAs barrier layers 4 and 8, the active region, and GaAs layers (with a high refractive index) 5-7 functions as an optical waveguide. Emitted photons are repeatedly reflected from these boundaries, propagating along the active region 6. The ends of the structure, created by cleaving the substrate, act as natural mirrors—a Fabry-Perot resonator 10.With sufficient pump power, a population inversion is achieved in the active region 6, and photons passing through the region with the inversion cause stimulated emission, and when the gain per pass in the resonator becomes greater than the losses, laser generation occurs, and coherent, monochromatic radiation emerges from the ends of the structure 10.

[0019] Thus, the proposed device is a monolithically integrated optical radiation source on a silicon substrate, providing generation in the near-infrared spectral region. The use of a (001)-oriented semiconductor silicon substrate with V-shaped notches ensures a low dislocation density, reduces the generation threshold and internal optical losses, and improves the homogeneity of the InAs quantum dots in the active region. The use of InAs quantum dots, which have low sensitivity to defects, further reduces the generation threshold and improves the temperature stability of the source.

[0020] Thus, the combination of an active medium based on quantum dots, which provides a high temperature generation threshold and a low threshold current density, with a Fabry-Perot resonator allows for a multiple increase in the energy efficiency of the device compared to similar devices.

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