A laser containing a population inversion structure

Abstract

The application discloses a laser containing a particle number inversion structure, which comprises, from bottom to top, a substrate, a lower limiting layer, a first lower waveguide layer, a second lower waveguide layer, an active layer, an upper waveguide layer and an upper limiting layer; the first lower waveguide layer and the second lower waveguide layer form a lower waveguide layer; the upper limiting layer, the upper waveguide layer, the active layer, the first lower waveguide layer and the second lower waveguide layer form a particle number inversion structure; in the particle number inversion structure, the upper waveguide layer steep Mg-doped concentration interface, the active layer steep Si-doped concentration interface, the lower waveguide layer steep Si-doped concentration interface, the upper waveguide layer steep Al content interface and the lower waveguide layer steep Al content interface jointly make the electron number of the active layer much larger than the hole number, thereby forming particle number inversion; with continuous input of an excitation source, hole radiation recombination is greater than loss, laser generation is accelerated, the threshold of the laser is reduced, and laser power and efficiency are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor optoelectronic devices, and in particular to a laser containing a population inversion structure. BACKGROUND

[0002] Lasers are widely used in laser display, laser television, laser projector, communication, medical treatment, weapon, guidance, distance measurement, spectrum analysis, cutting, precision welding, high-density optical storage and other fields. There are many types of lasers, and the classification methods are various. The main types of lasers include solid-state, gas, liquid, semiconductor and dye lasers. Compared with other types of lasers, all-solid-state semiconductor lasers have the advantages of small size, high efficiency, light weight, good stability, long service life, simple and compact structure, and small size.

[0003] At present, the nitride semiconductor laser has the following problems: 1) strong polarization effect caused by large internal lattice mismatch and large strain, QCSE quantum confinement Stark effect, which limits the improvement of the electric excitation gain of the laser; 2) high optical waveguide absorption loss, intrinsic carbon impurities in the p-type semiconductor can compensate the acceptor and destroy the p-type, the ionization rate of p-type doping is low, and a large number of un-ionized Mg acceptor impurities can cause internal optical loss to rise, and the refractive index dispersion of the laser limits the factor to decrease with the increase of wavelength, resulting in the decrease of the mode gain of the laser; 3) large Mg acceptor activation energy of the p-type semiconductor, low ionization efficiency, hole concentration far lower than electron concentration, hole mobility far less than electron mobility, and problems such as quantum well polarization field enhancing hole injection barrier, hole overflow active layer, etc. The uneven hole injection and low efficiency lead to serious asymmetry and mismatch of electrons and holes in the quantum well, electron leakage and carrier delocalization, and the hole transport in the quantum well is more difficult, the carrier injection is uneven, the gain is uneven, at the same time, the gain spectrum of the laser is broadened, the peak gain is decreased, resulting in the increase of the threshold current of the laser and the decrease of the slope efficiency. SUMMARY

[0004] The embodiment of the present application provides a laser element containing a spin spiral inductance layer, which forms a strong inductance strength in the laser element, and improves the optical power and the slope efficiency of the laser element.

[0005] To achieve the above-mentioned purpose, the embodiment of the present application provides a laser containing a population inversion structure, which comprises, from bottom to top, a substrate, a lower limiting layer, a first lower waveguide layer, a second lower waveguide layer, an active layer, an upper waveguide layer and an upper limiting layer; the first lower waveguide layer and the second lower waveguide layer form a lower waveguide layer.

[0006] The upper confining layer, the upper waveguide layer, the active layer, the first lower waveguide layer and the second lower waveguide layer form a population inversion structure, in which each growth parameter value is designed such that a descending angle of a Mg-doped concentration interface of the upper waveguide layer is greater than or equal to a preset threshold value, a descending angle of a Si-doped concentration interface of the active layer is greater than or equal to a preset threshold value, a descending angle of a Si-doped concentration interface of the lower waveguide layer is greater than or equal to a preset threshold value, a descending angle of an Al content interface of the upper waveguide layer is greater than or equal to a preset threshold value, and a descending angle of an Al content interface of the lower waveguide layer is greater than or equal to a preset threshold value.

[0007] In a possible implementation, in the population inversion structure, the Mg-doped concentration of the upper confining layer presents a linear descending trend in the direction of the upper waveguide layer, and a descending angle of a Mg-doped concentration interface is α, where α≥70°.

[0008] In a possible implementation, in the population inversion structure, the Si-doped concentration interface of the active layer presents an upward peak shape, the Si-doped concentration of the active layer presents a descending trend in the direction of the upper waveguide layer, a descending angle of a Si-doped concentration interface is β, where β≥70°, and the Si-doped concentration of the active layer presents a descending trend in the direction of the second lower waveguide layer, a descending angle of a Si-doped concentration interface is γ, where γ≥70°.

[0009] In a possible implementation, in the population inversion structure, the Si-doped concentration interface of the lower waveguide layer presents a downward peak shape, the Si-doped concentration presents a descending trend in the direction of the second lower waveguide layer to the first lower waveguide layer, a descending angle of a Si-doped concentration interface is δ, where δ≥70°, and the Si-doped concentration of the first lower waveguide layer presents a descending trend in the direction of the second lower waveguide layer, a descending angle of a Si-doped concentration interface is φ, where φ≥70°.

[0010] In a possible implementation, the Si-doped concentration of the Si-doped concentration interface of the active layer is 5E18-5E19 cm -3 ; the Si-doped concentration of the Si-doped concentration interface of the lower waveguide layer is 1E17-1E18 cm -3 ; the Si-doped concentration of the upper waveguide layer is 1E16-1E17 cm -3 ; the Si-doped concentration of the first lower waveguide layer is 5E17-1E19 cm -3 ; and the Si-doped concentration of the second lower waveguide layer is 1E18-1E19 cm -3 .

[0011] In a possible implementation, in the population inversion structure, the upper confining layer has a downward trend in Al content towards the upper waveguide layer, and a downward angle of the Al content interface is ψ, and ψ≥70°.

[0012] In a possible implementation, in the population inversion structure, the lower confining layer has a downward trend in Al content towards the first lower waveguide layer, and a downward angle of the Al content interface is θ, and θ≥70°.

[0013] In a possible implementation, the active layer is a periodic structure composed of four or fewer periodic layers, each periodic layer includes a well layer and a barrier layer, and different periodic layers are spliced to form a structure in which the well layer and the barrier layer are adjacent.

[0014] In a possible implementation, the lower confining layer, the lower waveguide layer, the active layer, the upper waveguide layer, or the upper confining layer includes one or more of GaN, AlGaN, InGaN, AlInGaN, AlN, InN, AlInN, SiC, Ga2O3, BN, GaAs, GaP, InP, AlGaAs, AlInGaAs, AlGaInP, InGaAs, AlInAs, AlInP, AlGaP, InGaP.

[0015] In a possible implementation, the substrate includes one or more of sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, SiO2, SiNx, magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2, and LiGaO2.

[0016] Compared with the prior art, the embodiment of the present application provides a laser containing a population inversion structure. The population inversion structure is formed by the upper confining layer, the upper waveguide layer, the active layer, the first lower waveguide layer, and the second lower waveguide layer. The components of each layer are adjusted to form the population inversion structure. In the population inversion structure, the upper waveguide layer Mg-doped interface with a certain inclination, the active layer Si-doped interface with a certain inclination, the lower waveguide layer Si-doped interface with a certain inclination, the upper waveguide layer Al content interface with a certain inclination, and the lower waveguide layer Al content interface with a certain inclination jointly form the population inversion. With continuous input of the excitation source, the electron-hole cavity radiation recombination is greater than the loss, the laser generation of stimulated emission is accelerated, the bipolar conductance is enhanced, the carrier concentration saturation and the carrier injection uniformity are improved, the laser voltage is reduced, meanwhile, the In segregation is reduced, the laser gain spectrum is narrowed, the peak gain and thermal stability are improved, the internal optical loss is reduced, the threshold of the laser is reduced, and the laser power and efficiency are improved. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1is an embodiment of the present application provides a kind of structure schematic diagram of laser containing particle number inversion structure;

[0018] Figure 2 is an embodiment of the present application provides a kind of structure SIMS secondary ion mass spectrum of semiconductor laser;

[0019] Figure 3 is an embodiment of the present application provides a kind of structure TEM transmission electron microscope test diagram of semiconductor laser. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0021] Please see Figure 1 , an embodiment of the present application provides a kind of laser containing particle number inversion structure, from below to above, including: substrate 100, lower limit layer 101, first lower waveguide layer 102, second lower waveguide layer 103, active layer 104, upper waveguide layer 105 and upper limit layer 106;The first lower waveguide layer 102 and the second lower waveguide layer 103 form lower waveguide layer.

[0022] The upper limit layer 106, the upper waveguide layer 105, the active layer 104, the first lower waveguide layer 102, the second lower waveguide layer 103 form particle number inversion structure 110, in the particle number inversion structure 110, the design each growth parameter value is that the descending angle of Mg doped concentration interface of the upper waveguide layer 105 is greater than or equal to the preset threshold value, the descending angle of Si doped concentration interface of the active layer 104 is greater than or equal to the preset threshold value, the descending angle of Si doped concentration interface of the lower waveguide layer is greater than or equal to the preset threshold value, the descending angle of Al content interface of the upper waveguide layer 105 is greater than or equal to the preset threshold value and the descending angle of Al content interface of the lower waveguide layer is greater than or equal to the preset threshold value.

[0023] Particle number inversion structure 110 is essentially a kind of double-exciton quantum confinement structure, in particle inversion, the steep Mg doped interface of the upper waveguide layer 105, the steep Si doped interface of the active layer 104, the steep Si doped interface of the lower waveguide layer jointly act, a large number of atoms in ground state are excited to metastable state, the number of photons absorbed from radiation field is always more than the number of photons generated by stimulated emission, so that the number of atoms in high energy level can be greatly more than the number of atoms in low energy level to form particle number inversion, and double-pole conductance is enhanced, carrier concentration saturation and carrier injection uniformity are improved, and laser voltage is reduced.

[0024] Secondly, the steep Al content interface of the upper waveguide layer 105 and the steep Al content interface of the lower waveguide layer improve the light field restriction effect, reduce internal optical loss, reduce the threshold of the laser, improve the laser power and efficiency, and enhance the pumping transport efficiency of particles to high energy levels, so that the low energy level particles of the active layer 104 are continuously pumped to high energy levels, the particle number inversion of the laser is maintained, the radiation recombination is greater than the loss, and the continuous stimulated emission of the laser is maintained.

[0025] The steep Mg doping interface of the upper waveguide layer 105, the steep Si doping interface of the active layer 104, the steep Si doping interface of the lower waveguide layer, the steep Al content interface of the upper waveguide layer 105, and the steep Al content interface of the lower waveguide layer can also reduce In segregation, reduce laser spectral broadening, narrow the gain spectrum of the laser, and improve the peak gain and thermal stability.

[0026] In summary, the particle number inversion structure 110 formed by the steep Mg doping interface of the upper waveguide layer 105, the steep Si doping interface of the active layer 104, the steep Si doping interface of the lower waveguide layer, the steep Al content interface of the upper waveguide layer 105, and the steep Al content interface of the lower waveguide layer forms a particle number inversion inside the laser. With the continuous input of the excitation source, the electron hole radiation recombination is greater than the loss, the laser generates stimulated emission faster, the bipolar conductance is enhanced, the carrier concentration saturation and carrier injection uniformity are improved, the laser voltage is reduced, and at the same time, the In segregation is reduced, the gain spectrum of the laser is narrowed, the peak gain and thermal stability are improved, the internal optical loss is reduced, the threshold of the laser is reduced, and the laser power and efficiency are improved.

[0027] It should be noted that the design of each growth parameter value includes but is not limited to: adjusting the Mg doping concentration, the Si doping concentration, and the Al content by means of Mg flow, Si flow, TMAl flow, Mg / Ga ratio, Mg / Al ratio, Si / Ga ratio, Si / Al ratio, growth temperature, growth rate, temperature, pressure, rotation speed, VIII ratio, N2 / H2 flow, Ramp change rate, etc. to finally achieve the designed steep interface of the doping concentration.

[0028] Exemplarily, in the particle number inversion structure 110, the Mg doping concentration of the upper confinement layer 106 in the direction of the upper waveguide layer 105 shows a linear downward trend, and the downward angle of the Mg doping concentration interface is a, a≥70°.

[0029] Exemplarily, please refer to Figure 2In the particle number inversion structure 110, the Si doping concentration interface of the active layer 104 presents an upward sharp peak, the Si doping concentration of the active layer 104 decreases in the direction of the upper waveguide layer 105, the downward angle of the Si doping concentration interface is β, and β≥70°; the Si doping concentration of the active layer 104 decreases in the direction of the second lower waveguide layer 103, the downward angle of the Si doping concentration interface is γ, and γ≥70°.

[0030] In the particle number inversion structure 110, the Si doping concentration interface of the lower waveguide layer presents a downward sharp peak, the Si doping concentration decreases in the direction of the first lower waveguide layer 102 from the second lower waveguide layer 103, the downward angle of the Si doping concentration interface is δ, and δ≥70°; the Si doping concentration decreases in the direction of the second lower waveguide layer 103 from the first lower waveguide layer 102, the downward angle of the Si doping concentration interface is φ, and φ≥70°.

[0031] In the Si doping concentration interface of the active layer 104, the Si doping concentration is 5E18-5E19cm -3 In the Si doping concentration interface of the lower waveguide layer, the Si doping concentration is 1E17-1E18cm -3 The Si doping concentration of the upper waveguide layer 105 is 1E16-1E17cm -3 The Si doping concentration of the first lower waveguide layer 102 is 5E17-1E19cm -3 The Si doping concentration of the second lower waveguide layer 103 is 1E18-1E19cm -3 .

[0032] The Si doping concentration used in the embodiment is the optimal value optimized according to the experimental DOE result, and in actual application, a technician can adjust it according to the demand.

[0033] In the particle number inversion structure 110, the Al content of the upper limiting layer 106 decreases in the direction of the upper waveguide layer 105, the downward angle of the Al content interface is ψ, and ψ≥70°.

[0034] In the particle number inversion structure 110, the Al content of the lower limiting layer 101 decreases in the direction of the first lower waveguide layer 102, the downward angle of the Al content interface is θ, and θ≥70°.

[0035] In the above embodiment, the downward angle is generally set to 70, and the purpose of this is to ensure the steepness of Mg doping; any angle greater than or equal to 70 degrees can also be set.

[0036] In the particle number inversion structure 110, the Al content of the upper limiting layer 106 decreases in the direction of the upper waveguide layer 105, the downward angle of the Al content interface is ψ, and ψ≥70°. Figure 3The active layer 104 is a periodic structure composed of four or less periodic layers, each of which includes a well layer and a barrier layer, and the different periodic layers are spliced to form a structure in which the well layer and the barrier layer are adjacent.

[0037] Generally, the thickness of the well layer of the active layer 104 is a: 40≤a≤80 angstroms, and the thickness of the barrier layer is b: 10≤b≤40 angstroms, and the thickness of the well layer is greater than or equal to the thickness of the barrier layer.

[0038] Under the action of the particle number inversion structure 110, the H impurity concentration of the upper limiting layer 106, the upper waveguide layer 105, the active layer 104, the first lower waveguide layer 102, the second lower waveguide layer 103, and the lower limiting layer 101 in the above embodiment is in a U-shaped distribution; the H impurity concentration distribution is: upper limiting layer 106≥lower limiting layer 101≥upper waveguide layer 105-active layer 104-first lower waveguide layer 102-second lower waveguide layer 103(near the interface of the upper limiting layer 106 20nm signal is not calculated).

[0039] The O impurity concentration is in a U-shaped distribution; the O impurity concentration distribution is: upper limiting layer 106≥lower limiting layer 101≥upper waveguide layer 105-active layer 104-first lower waveguide layer 102-second lower waveguide layer 103(near the interface of the upper limiting layer 106 20nm signal is not calculated).

[0040] The C impurity concentration is in a U-shaped distribution; the C impurity concentration distribution is: lower limiting layer 101≥upper limiting layer 106≥upper waveguide layer 105-active layer 104-first lower waveguide layer 102-second lower waveguide layer 103(near the interface of the upper limiting layer 106 20nm signal is not calculated).

[0041] Exemplarily, the lower limiting layer 101 or the lower waveguide layer or the active layer 104 or the upper waveguide layer 105 or the upper limiting layer 106 includes one component or multiple components of GaN, AlGaN, InGaN, AlInGaN, AlN, InN, AlInN, SiC, Ga2O3, BN, GaAs, GaP, InP, AlGaAs, AlInGaAs, AlGaInP, InGaAs, AlInAs, AlInP, AlGaP, InGaP.

[0042] Exemplarily, the substrate 100 includes one component or multiple components of sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, SiO2, SiNx, magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2, and LiGaO2.

[0043] Through the comparative analysis of the experimental data of the laser in the above embodiment and the conventional laser, Table 1 can be obtained. The particle number inversion structure 110 is constructed by the steep Mg doping concentration interface of the upper waveguide layer 105, the steep Si doping concentration interface of the active layer 104, the steep Si doping concentration interface of the lower waveguide layer, the steep Al content interface of the upper waveguide layer 105 and the steep Al content interface of the lower waveguide layer, so that the number of electrons of the active layer 104 is much larger than the number of holes to form particle number inversion. With the continuous input of the excitation source, the electron-hole radiation recombination is greater than the loss, the laser generates stimulated emission is accelerated, the threshold of the laser is reduced, and the laser power and efficiency are improved.

[0044] Table 1: Comparison of laser parameters

[0045] Blue laser - project Conventional laser Laser of the present application Variation amplitude Beam quality factor M 2 ]]> 3.7 2.1 76％ Slope efficiency (W / A) 1.2 1.8 50％ threshold current density (kA / cm 2 )]]> 1.8 0.8 -56％ Optical power (W) 3.3 4.9 48％ Limiting factor 1.40％ 2.20％ 57％ Internal optical loss (cm -1 )]]> 20.1 11.8 -41％ External quantum efficiency 27.50％ 38.50％ 40％

[0046] Compared with the prior art, the embodiment of the present application provides a laser containing a particle number inversion structure 110. The particle number inversion structure 110 is formed by the upper confinement layer 106, the upper waveguide layer 105, the active layer 104, the first lower waveguide layer 102 and the second lower waveguide layer 103. The composition of each layer is adjusted to form the particle number inversion structure 110. In the particle number inversion structure 110, the certain inclination of the Mg doping interface of the upper waveguide layer 105, the certain inclination of the Si doping interface of the active layer 104, the certain inclination of the Si doping interface of the lower waveguide layer, the certain inclination of the Al content interface of the upper waveguide layer 105 and the certain inclination of the Al content interface of the lower waveguide layer jointly act to form particle number inversion. With the continuous input of the excitation source, the electron-hole radiation recombination is greater than the loss, the laser generates stimulated emission is accelerated, the bipolar conductance is enhanced, the carrier concentration saturation and the carrier injection uniformity are improved, the laser voltage is reduced, the In segregation is reduced, the laser gain spectrum is narrowed, the peak gain and thermal stability are improved, the internal optical loss is reduced, the threshold of the laser is reduced, and the laser power and efficiency are improved.

[0047] The above is the preferred embodiment of the present application. It should be noted that for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, which are also considered within the scope of protection of the present application.

Claims

1. A laser containing a population inversion structure, characterized in that, From bottom to top, it includes: a substrate, a lower confinement layer, a first lower waveguide layer, a second lower waveguide layer, an active layer, an upper waveguide layer, and an upper confinement layer; the first lower waveguide layer and the second lower waveguide layer form the lower waveguide layer; The upper confinement layer, the upper waveguide layer, the active layer, the first lower waveguide layer, and the second lower waveguide layer form a population inversion structure. In the population inversion structure, various growth parameter values ​​are designed such that the descent angle of the Mg doping concentration interface of the upper waveguide layer is greater than or equal to a preset threshold, the descent angle of the Si doping concentration interface of the active layer is greater than or equal to a preset threshold, the descent angle of the Si doping concentration interface of the lower waveguide layer is greater than or equal to a preset threshold, the descent angle of the Al content interface of the upper waveguide layer is greater than or equal to a preset threshold, and the descent angle of the Al content interface of the lower waveguide layer is greater than or equal to a preset threshold. In the population inversion structure, the Mg doping concentration in the upper confinement layer decreases linearly towards the upper waveguide layer, with a decrease angle of α at the Mg doping concentration interface, where α ≥ 70°. The Si doping concentration in the active layer exhibits an upward spike, and the Si doping concentration in the active layer decreases towards the upper waveguide layer, with a decrease angle of β at the Si doping concentration interface, where β ≥ 70°. The Si doping concentration in the active layer decreases towards the second lower waveguide layer, with a decrease angle of γ at the Si doping concentration interface, where γ ≥ 70°. The Si doping concentration in the lower waveguide layer exhibits a downward spike. In the direction from the second lower waveguide layer to the first lower waveguide layer, the Si doping concentration decreases, and the angle of decrease at the Si doping concentration interface is δ, where δ ≥ 70°; in the direction from the first lower waveguide layer to the second lower waveguide layer, the Si doping concentration decreases, and the angle of decrease at the Si doping concentration interface is φ, where φ ≥ 70°; in the direction from the upper confinement layer to the upper waveguide layer, the Al content decreases, and the angle of decrease at the Al content interface is ψ, where ψ ≥ 70°; in the direction from the lower confinement layer to the first lower waveguide layer, the Al content decreases, and the angle of decrease at the Al content interface is θ, where θ ≥ 70°.

2. The laser with a population inversion structure as described in claim 1, characterized in that, The Si doping concentration at the Si doping concentration interface of the active layer is 5E18~5E19 cm⁻¹. -3 The Si doping concentration at the interface of the lower waveguide layer is 1E17 to 1E18 cm⁻¹. -3 The Si doping concentration of the upper waveguide layer is 1E16~1E17 cm⁻¹. -3 The Si doping concentration of the first lower waveguide layer is 5E17 to 1E19 cm⁻¹. -3 The Si doping concentration of the second lower waveguide layer is 1E18~1E19 cm⁻¹. -3 .

3. The laser with a population inversion structure as described in claim 1, characterized in that, The active layer is a periodic structure consisting of four or fewer periodic layers. Each periodic layer includes a well layer and a barrier layer. When different periodic layers are spliced ​​together, a structure is formed in which the well layer and the barrier layer are adjacent.

4. The laser with a population inversion structure as described in claim 1, characterized in that, The lower confinement layer, the lower waveguide layer, the active layer, the upper waveguide layer, or the upper confinement layer comprises one or more components selected from GaN, AlGaN, InGaN, AlInGaN, AlN, InN, AlInN, SiC, Ga2O3, BN, GaAs, GaP, InP, AlGaAs, AlInGaAs, AlGaInP, InGaAs, AlInAs, AlInP, AlGaP, and InGaP.

5. The laser with a population inversion structure as described in claim 1, characterized in that, The substrate comprises one or more of the following components: sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, SiO2, SiNx, magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2, and LiGaO2.

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