JP2019029522A - Light emitting device and projector - Google Patents

Abstract

To provide a light emitting device that can gather current to a specific columnar part.SOLUTION: A light emitting device comprises a substrate and a laminate provided on the substrate. The laminate has a plurality of first columnar parts and second columnar parts. The minimum diameter of the first columnar part has a length of a depletion layer area in the radial direction of the first columnar part, and the minimum diameter of the second columnar part is larger than the length of a depletion layer area in the radial direction of the second columnar part.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a light emitting device and a projector.

  In a surface emitting laser (VCSEL), current confinement for concentrating current in a minute region is an important technique for improving characteristics. As methods for realizing such current confinement, there are known a method in which a side surface of a resonator (cavity) is exposed by etching, and a method in which resistance is increased by ion implantation.

  On the other hand, as a next generation light source with high brightness, a light emitting device using a nanostructure (nanocolumn) is expected. For example, Patent Document 1 describes a light emitting device having a GaN nanocolumn.

JP 2009-152474 A

  Also in the light emitting device having the nanocolumn (columnar portion) as described above, a technique for concentrating current in a minute region (in a specific columnar portion) is required as in the surface emitting laser.

  One of the objects according to some embodiments of the present invention is to provide a light-emitting device capable of concentrating current on a specific columnar portion. Alternatively, one of the objects according to some aspects of the present invention is to provide a projector including the light-emitting device.

The light emitting device according to the present invention is
A substrate;
A laminate provided on the substrate;
Have
The laminate includes a plurality of first columnar portions and second columnar portions,
The minimum diameter of the first columnar part is the length of the depletion layer region in the radial direction of the first columnar part,
The minimum diameter of the second columnar part is larger than the length of the depletion layer region in the radial direction of the second columnar part.

  In such a light emitting device, the resistance in the stacking direction of the first columnar part can be sufficiently increased as compared with the resistance in the stacking direction of the second columnar part. Therefore, in such a light emitting device, it is possible to reduce the current flowing through the first columnar part and concentrate the current on the second columnar part.

In the light emitting device according to the present invention,
The laminate is
A first region provided with the first columnar part;
A second region provided with the second columnar portion;
Have
The first region may surround the second region as viewed from the stacking direction of the stacked body.

  In such a light emitting device, the light generated in the active layer of the second columnar portion can be confined in the second region as seen from the stacking direction of the stacked body, and laser oscillation can be performed.

In the light emitting device according to the present invention,
The laminate is
A first region provided with the first columnar part;
A second region provided with the second columnar portion;
Have
Two first regions are provided,
The second region may be provided between the two first regions when viewed from the stacking direction of the stacked body.

  In such a light emitting device, the light generated in the active layer of the second columnar portion can be laser-oscillated by multiple reflection between the two first regions when viewed from the stacking direction of the stacked body.

In the light emitting device according to the present invention,
Having an electrode provided on the side opposite to the substrate side of the laminate,
The electrode is provided with an opening,
The opening may overlap the second columnar part as viewed from the stacking direction of the stacked body.

  In such a light emitting device, light generated in the active layer of the second columnar portion can be suppressed from being absorbed by the second electrode.

In the light emitting device according to the present invention,
The laminate may include a first mirror layer and a second mirror layer that sandwich the second columnar part.

  In such a light emitting device, the light generated in the active layer of the second columnar portion can be laser-oscillated by multiple reflection between the first mirror layer and the second mirror layer.

In the light emitting device according to the present invention,
A plurality of the second columnar portions may be provided.

  In such a light emitting device, for example, the effect of the photonic crystal can be exhibited by adjusting the size and pitch of the second columnar portion in the planar direction (direction orthogonal to the stacking direction).

In the light emitting device according to the present invention,
An interval between the adjacent first columnar portions may be larger than an interval between the adjacent second columnar portions.

  In such a light-emitting device, the average refractive index of the active layer and air in the first region can be more reliably lowered than the average refractive index of the active layer and air in the second region.

The projector in the light emitting device according to the present invention is:
The light emitting device according to the present invention is included.

  Such a projector can include the light emitting device according to the present invention.

Sectional drawing which shows typically the light-emitting device which concerns on 1st Embodiment. The top view which shows typically the light-emitting device which concerns on 1st Embodiment. The figure for demonstrating the depletion layer area | region of the 1st columnar part of the light-emitting device which concerns on 1st Embodiment. The figure for demonstrating the depletion layer area | region of the 2nd columnar part of the light-emitting device which concerns on 1st Embodiment. The graph which shows the relationship between the carrier concentration of 1st semiconductor layer which comprises a columnar part, and (root) (alpha). The graph which shows the relationship between the diameter and resistivity of the 1st semiconductor layer which comprises a columnar part. Sectional drawing which shows typically the manufacturing process of the light-emitting device which concerns on 1st Embodiment. Sectional drawing which shows typically the light-emitting device which concerns on the 1st modification of 1st Embodiment. The top view which shows typically the light-emitting device which concerns on the 2nd modification of 1st Embodiment. Sectional drawing which shows typically the light-emitting device which concerns on 2nd Embodiment. Sectional drawing which shows typically the light-emitting device which concerns on the modification of 2nd Embodiment. The figure which shows typically the projector which concerns on 3rd Embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. The embodiments described below do not unduly limit the contents of the present invention described in the claims. In addition, not all of the configurations described below are essential constituent requirements of the present invention.

1. 1. First embodiment 1.1. First, the light emitting device according to the first embodiment will be described with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing a light emitting device 100 according to the first embodiment. FIG. 2 is a plan view schematically showing the light emitting device 100 according to the first embodiment. 1 is a cross-sectional view taken along the line II of FIG.

  As illustrated in FIGS. 1 and 2, the light emitting device 100 includes a base body 10, a stacked body 20, a first electrode 50, and a second electrode 52. For convenience, the second semiconductor layer 44 and the second electrode 52 of the stacked body 20 are not shown in FIG.

  The base 10 has, for example, a plate shape. The base 10 is, for example, a Si substrate, a GaN substrate, a sapphire substrate, or the like.

 The stacked body 20 is provided on the base 10 (on the base 10). The stacked body 20 includes a buffer layer 22, a first columnar portion 30, and a second columnar portion 32.

  In the present invention, “above” refers to a direction away from the substrate 10 when viewed from the active layer 42 of the stacked body 20 in the stacking direction of the stacked body 20 (hereinafter, also simply referred to as “laminated direction”). “Lower” means a direction approaching the substrate 10 as viewed from the active layer 42 in the stacking direction.

  In the present invention, the “stacking direction of the stacked body 20” refers to the stacking direction (vertical direction in the illustrated example) of the first semiconductor layer 40 and the active layer 42 of the stacked body 20.

  The buffer layer 22 is provided on the substrate 10. The buffer layer 22 is, for example, a first conductivity type (eg, n-type) GaN layer (specifically, a GaN layer doped with Si).

  The first columnar part 30 and the second columnar part 32 are provided on the buffer layer 22. The stacked body 20 includes a first region 2 in which the first columnar portion 30 is provided and a second region 4 in which the second columnar portion 32 is provided. In the illustrated example, the buffer layer 22 has a first region 2 and a second region 4. The first region 2 surrounds the second region 4 when viewed from the stacking direction (in plan view). The first columnar part 30 has a columnar shape protruding upward from the first region 2. The second columnar part 32 has a columnar shape protruding upward from the second region 4.

  A plurality of first columnar portions 30 are provided. A plurality of second columnar portions 32 are provided. For example, the plurality of second columnar portions 32 are arranged at a predetermined pitch in a predetermined direction in plan view. In the illustrated example, the plurality of second columnar portions 32 are arranged in a regular triangular lattice shape in plan view. The planar shape (the shape seen from the stacking direction) of the columnar parts 30 and 32 is, for example, a hexagon (specifically, a regular hexagon).

  The first columnar part 30 and the second columnar part 32 have a first semiconductor layer 40, an active layer 42, and a second semiconductor layer 44.

  The first semiconductor layer 40 is provided on the buffer layer 22. The first semiconductor layer 40 is, for example, a first conductivity type (for example, n-type) GaN layer (specifically, a GaN layer doped with Si), an AlGaN layer, or the like.

  The active layer 42 is provided on the first semiconductor layer 40. The active layer 42 is provided between the first semiconductor layer 40 and the second semiconductor layer 44. The active layer 42 is a layer that can emit light when current is injected. The active layer 42 has, for example, a quantum well (MQW) structure composed of a GaN layer and an InGaN layer. The number of GaN layers and InGaN layers constituting the active layer 42 is not particularly limited.

  The second semiconductor layer 44 is provided on the active layer 42. The second semiconductor layer 44 is, for example, a second conductivity type (for example, p-type) GaN layer (specifically, a GaN layer doped with Mg), an AlGaN layer, or the like. The semiconductor layers 40 and 44 are, for example, cladding layers having a function of confining light in the active layer 42 (suppressing light leakage from the active layer 42).

  The minimum diameter of the first columnar part 30 is smaller than the minimum diameter of the second columnar part 32. In the first columnar part 30, the diameter of the second semiconductor layer 44 is larger than the diameters of the active layer 42 and the first semiconductor layer 40, for example. In the illustrated example, in the first columnar section 30, the diameter of the active layer 42 and the diameter of the first semiconductor layer 40 are the same. Similarly, in the second columnar section 32, the diameter of the second semiconductor layer 44 is larger than the diameters of the active layer 42 and the first semiconductor layer 40, for example, and the diameter of the active layer 42 and the diameter of the first semiconductor layer 40 are Are the same. The second semiconductor layer 44 has a portion whose diameter gradually increases upward (from the active layer 42 side toward the second electrode 52 side).

  In the present invention, the “diameter” is the diameter of the smallest circle (minimum inclusion circle) including the polygon when the planar shape of the columnar portions 30 and 32 is a polygon as shown in FIG. It is. Although not shown, when the planar shape of the columnar portions 30 and 32 is a circle, the “diameter” is a diameter.

  In the present invention, the “minimum diameter” is the minimum diameter in the columnar portions 30 and 32. In the illustrated example, the minimum diameter is the diameter of the active layer 42 or the diameter of the first semiconductor layer 40.

The minimum diameter of the first columnar part 30 and the second columnar part 32 is, for example, on the order of nm. The columnar portions 30 and 32 are also called, for example, nanocolumns, nanowires, nanorods, and nanopillars. The size of the columnar portions 30 and 32 in the stacking direction is, for example, not less than 0.1 μm and not more than 5 μm. The interval between the adjacent first columnar portions 30 is larger than the interval between the adjacent second columnar portions 32. The interval between the adjacent first columnar portions 30 is, for example, not less than 10 nm and not more than 500 nm. The interval between the adjacent second columnar portions 32 is, for example, not less than 1 nm and not more than 300 nm.

The average refractive index between the active layer 42 and air (void) in the first region 2 is lower than the average refractive index between the active layer 42 and air in the second region 4. The “average refractive index of the active layer 42 and air in the first region 2” refers to an imaginary plane (a plane having a normal line in the stacking direction) that passes through the active layer 42 and overlaps the first region 2 in plan view. It is an average refractive index of the active layer 42 and air. The same applies to “the average refractive index of the active layer 42 and air (voids) in the second region 4”. Specifically, the average refractive index n _AVE is expressed as the following formula (1).

However, in Formula (1), ε ₁ is the dielectric constant of the active layer 42. φ is a filling factor (ratio of the area of the active layer 42 to the area of the virtual plane) in the virtual plane (a virtual plane overlapping the first region 2 in plan view). ε _AIR is the dielectric constant of air. When a predetermined member is provided instead of air, the average refractive index n _AVE can be obtained by substituting the dielectric constant ε _AIR of air with the dielectric constant of the member in Equation (1).

  The first columnar part 30 and the second columnar part 32 have a depletion layer region. Here, FIG. 3 is a cross-sectional view for explaining the depletion layer region 34 of the first columnar portion 30. FIG. 4 is a cross-sectional view for explaining the depletion layer region 34 of the second columnar portion 32. For convenience, the depletion layer region 34 is not shown in FIG. 1 and FIGS.

Minimum diameter D ₁ of the first columnar portion 30, as shown in FIG. 3, (a direction perpendicular to the stacking direction, the plane direction) radial direction of the first columnar portion 30 is a length of the depletion region 34. Portion constituting the minimum diameter D ₁ of the first columnar portion 30 (which is filled by the depletion region 34) is a depletion region 34. In the illustrated example, the portion constituting the minimum diameter D ₁ of the first columnar portion 30 is the first semiconductor layer 40, and the first semiconductor layer 40 is the depletion layer region 34.

Minimum diameter D ₂ of the second columnar portion 32, as shown in FIG. 4, greater than the radial length of the depletion layer region 34 of the second columnar portion 32 (2 × L). A portion constituting the minimum diameter D ₂ of the second columnar portion 32 is not filled with the depletion layer region 34. In the illustrated example, the portion constituting the minimum diameter D ₂ of the second columnar portion 32 is the first semiconductor layer 40, and the first semiconductor layer 40 forms a depletion layer region 34 and a depletion layer region 34. Non-depleted layer region 36.

Note that “the length of the depletion layer region 34 in the radial direction” refers to the diameter of the non-depletion layer region 36 (when the planar shape of the non-depletion layer region is a polygon) from the minimum diameter D ₂ of the second columnar portion 32. , the diameter of the inscribed circle of the polygon, in the case of a circle is a value obtained by subtracting the diameter) D _3.

The depletion layer region 34 is a region where carriers generated near the side surfaces of the columnar portions 30 and 32 are depleted by Fermi-level pinning. As shown in FIG. 3, when the first semiconductor layer 40 is filled with the depletion layer region 34, the resistance when a current flows in the stacking direction of the first semiconductor layer 40 becomes a high resistance. The resistance _RNW per one first semiconductor layer 40 not filled with the depletion layer region 34 is expressed by the following formula (2).

However, in Formula (2), l _NW is the length of the first semiconductor layer 40 in the stacking direction. q is an elementary electric quantity. N is the carrier concentration of the first semiconductor layer 40. μ is the mobility of the first semiconductor layer 40. r is a half value of the diameter of the first semiconductor layer 40 constituting the columnar portions 30 and 32. ε ₀ is the dielectric constant of vacuum. ε _r is the relative dielectric constant of the first semiconductor layer 40. ψ is the surface potential of the first semiconductor layer 40.

In equation (2), when r is decreased, R _NW increases rapidly when r approaches √α (the square root of α, where α = (2ε ₀ ε _r ψ) / (qN)). . The minimum diameter of the first columnar portion 30 is a value of 2√α or less. The minimum diameter of the second columnar portion 32 is a value larger than 2√α.

Here, FIG. 5 is a graph showing the relationship between the carrier concentration N and √α. Figure 6 is a graph showing the relationship between the resistance R _NW minimum diameter (diameter of the first semiconductor layer) 2r and the first semiconductor layer of the columnar portion. In FIG. 5, the material of the first semiconductor layer is Si-doped GaN (Si-doped GaN), ε ₀ = 8.85 × 10 ⁻¹² Fm ⁻¹ , ε _r = 8.9, q = 1.6 The calculation was performed with × 10 ⁻¹⁹ C and ψ = 0.55 eV. In addition to the values in FIG. 5, in FIG. 6, the following formula (3) [O. Benner et al. , Applied Physics Letters 107, 082103 (2015)]]. The vertical axis of FIG. 6 is a resistivity multiplied by the area pi] r ² by dividing the _{R NW} length _{l NW} of formula (2).

  In FIG. 5, in the region below the solid line (oblique line), the diameter of the first semiconductor layer 40 constituting the columnar portion is the length of the depletion layer region 34 (the length of the depletion layer region 34 in the radial direction of the columnar portion). This is the area. In this region, the first semiconductor layer 40 is a depletion layer region 34.

  In FIG. 5, the region above the solid line is a region where the diameter of the first semiconductor layer 40 is larger than the length of the depletion layer region 34. In this region, the first semiconductor layer 40 has a depletion layer region 34 and a non-depletion layer region 36.

For example, when the carrier concentration N is 1 × 10 ¹⁸ (cm ⁻³ ), the radius of the first semiconductor layer 40 is 23 nm (diameter is 46 nm) or less, and the diameter of the first semiconductor layer 40 is the length of the depletion layer region 34. It becomes. When the carrier concentration N is 1 × 10 ¹⁸ (cm ⁻³ ), the minimum diameter D ₁ of the first columnar part 30 is 46 nm or less, and the minimum diameter D ₂ of the second columnar part 32 is larger than 46 nm.

As shown in FIG. 6, it can be seen that the resistance _RNW increases rapidly as the diameter of the first semiconductor layer 40 constituting the columnar portion is reduced. Normally, the resistance is inversely proportional to the cross-sectional area of the first semiconductor layer 40 (cross-sectional area when cut along a plane having a normal line in the stacking direction), and when the cross-sectional area is halved, the resistance is doubled. However, when the diameter of the first semiconductor layer 40 becomes the length of the depletion layer region 34, the above correlation is lost and the resistance increases rapidly.

  For example, the resistance in the stacking direction of the first semiconductor layer of the first columnar part and the resistance in the stacking direction of the first semiconductor layer of the second columnar part are measured, and the above correlation between the cross-sectional area and the resistance can be eliminated. For example, the diameter of the first semiconductor layer of the first columnar portion may be the length of the depletion layer region. The first semiconductor layer can be cut out using, for example, a focused ion beam (FIB).

Further, √α is obtained from the relative dielectric constant ε _r of the first semiconductor layer, the surface potential ψ, and the carrier concentration N, and if the obtained √α is in a region below the solid line in the graph of FIG. The diameter may be the length of the depletion layer region. The carrier concentration N can be obtained from, for example, EDX (Energy dispersive X-ray spectroscopy).

  In the light emitting device 100, the p-type second semiconductor layer 44, the active layer 42 not doped with impurities, and the n-type first semiconductor layer 40 constitute a pin diode. Each of the first semiconductor layer 40 and the second semiconductor layer 44 is a layer having a larger band gap than the active layer 42. In the light emitting device 100, when a forward bias voltage of a pin diode is applied between the first electrode 50 and the second electrode 52, the first semiconductor layer 40 of the first columnar part 30 has a high resistance, so that the current is second. It concentrates on the columnar part 32. Then, recombination of electrons and holes occurs in the active layer 42 of the second columnar portion 32. This recombination causes light emission.

  Light generated in the active layer 42 of the second columnar portion 32 propagates in the plane direction by the semiconductor layers 40 and 44 and is reflected when reaching the first columnar portion 30. The light generated in the active layer 42 of the second columnar portion 32 is transmitted to the first columnar portion 30 provided in the first region 2 located on one side of the second region 4 and to the other side of the second region 4. A standing wave is formed by multiple reflection between the first columnar part 30 provided in the first region 2 and the laser is oscillated by receiving a gain in the active layer 42.

  The light emitting device 100 emits the + 1st order diffracted light and the −1st order diffracted light as laser light in the stacking direction (to the second electrode 52 side and the substrate 10 side). For example, by adjusting the size and pitch of the second columnar portion 32 in the planar direction, the light that is multiply reflected receives the effect of the photonic crystal by the second columnar portion 32, and the + 1st order diffracted light and the −1st order diffracted light Is emitted in the laminating direction as a laser beam.

  Although not shown, a mirror layer may be provided between the base 10 and the first semiconductor layer 40 or below the base 10. The mirror layer is, for example, a distributed Bragg reflection (DBR) mirror. The light generated in the active layer 42 can be reflected by the mirror layer, and the light emitting device 100 can emit light only from the second electrode 52 side.

  The first electrode 50 is provided on the buffer layer 22. In the illustrated example, the first electrode 50 is provided in the third region 6 of the buffer layer 22. The third region 6 is a region different from the first region 2 and the second region 4. The third region 6 may be in ohmic contact with the first electrode 50. The first electrode 50 is electrically connected to the first semiconductor layer 40. In the illustrated example, the first electrode 50 is electrically connected to the first semiconductor layer 40 via the buffer layer 22. The first electrode 50 is one electrode for injecting a current into the active layer 42. As the 1st electrode 50, what laminated | stacked in order of Ti layer, Al layer, and Au layer from the 3rd area | region 6 side is used, for example.

Although not shown, a first contact layer may be provided between the first electrode 50 and the buffer layer 22. The first contact layer may be in ohmic contact with the first electrode 50. The first contact layer may be an n-type GaN layer. When the substrate 10 is conductive, the first electrode 50 may be provided under the substrate 10 although not shown.

  The second electrode 52 is provided on the second semiconductor layer 44. The second electrode 52 is provided on the opposite side of the laminated body 20 from the base 10 side. The second electrode 52 is electrically connected to the second semiconductor layer 44. In the illustrated example, the second electrode 52 is provided above the second columnar portion 32 (above the second region 4). The second electrode 52 is the other electrode for injecting current into the active layer 42. The second electrode 52 is a transparent electrode such as ITO (Indium Tin Oxide). Thereby, the light emitted from the active layer 42 can be transmitted through the second electrode 52 and emitted.

  Although not shown, a second contact layer may be provided between the second electrode 52 and the second semiconductor layer 44. The second contact layer may be in ohmic contact with the second electrode 52. The second contact layer may be a p-type GaN layer.

  In the above description, the InGaN-based active layer 42 has been described. However, any material system that can emit light when current is injected can be used as the active layer 42. For example, semiconductor materials such as AlGaN, AlGaAs, InGaAs, InGaAsP, InP, GaP, and AlGaP can be used.

  For example, the light emitting device 100 has the following characteristics.

  In the light emitting device 100, the minimum diameter of the first columnar portion 30 is the length of the depletion layer region 34 in the radial direction of the first columnar portion 30, and the minimum diameter of the second columnar portion 32 is that of the second columnar portion 32. It is larger than the length of the depletion layer region 34 in the radial direction. Therefore, in the light emitting device 100, the resistance in the stacking direction of the first columnar section 30 is sufficiently higher than the resistance in the stacking direction of the second columnar section 32 (for example, “the resistance is doubled when the cross-sectional area is halved). Can be increased). Therefore, in the light emitting device 100, the current flowing through the first columnar part 30 can be reduced and the current can be concentrated on the second columnar part 32. Thus, the light emitting device 100 can have a highly accurate current confinement mechanism that can concentrate current in units of columnar portions. Thereby, in the light emitting device 100, for example, the current density flowing in the second columnar part 32 can be increased, and the light extraction efficiency can be improved. Further, in the light emitting device 100, as shown in FIG. 1, even if the second electrode 52 is provided on the second columnar portion 32, the current can be concentrated on the two columnar portions 32. The positional accuracy can be relaxed.

  In the light emitting device 100, the first region 2 surrounds the second region 4 in plan view. Here, since the first columnar portion 30 provided in the first region 2 has a smaller diameter than the second columnar portion 32 provided in the second region 4, for example, the active layer 42 in the first region 2 is used. The average refractive index of air and air is lower than the average refractive index of the active layer 42 and air in the second region 4. Therefore, in the light emitting device 100, the light generated in the active layer 42 of the second columnar portion 32 can be confined in the second region 4 in a plan view, and laser oscillation can be performed. For example, the plurality of first columnar portions 30 have a photonic band gap structure, the second columnar portions 32 function as photonic crystal defects, and can confine light in the second region 4 in plan view. . Thereby, in the light-emitting device 100, the directivity of the emitted light can be controlled, for example.

In the light emitting device 100, a plurality of second columnar portions 32 are provided. Therefore, for example, by adjusting the size and pitch of the second columnar portion 32 in the planar direction, the light emitting device 100 can exhibit the effect of the photonic crystal. Although not shown, the second columnar section 32
There may be provided only one rather than a plurality. Thereby, for example, a single photon generating element can be configured.

  In the light emitting device 100, the interval between the adjacent first columnar portions 30 is larger than the interval between the adjacent second columnar portions 32. Therefore, in the light emitting device 100, the average refractive index of the active layer 42 and air in the first region 2 can be more reliably lowered than the average refractive index of the active layer 42 and air in the second region 4. .

  The light emitting device according to the present invention may be an LED (Light Emitting Diode) instead of a semiconductor laser that emits laser light.

1.2. Method for Manufacturing Light-Emitting Device Next, a method for manufacturing the light-emitting device 100 according to the first embodiment will be described with reference to the drawings. FIG. 7 is a cross-sectional view schematically showing the manufacturing process of the light emitting device 100 according to the first embodiment.

  As shown in FIG. 7, the buffer layer 22 is epitaxially grown on the substrate 10. Examples of the epitaxial growth method include a MOCVD (Metal Organic Chemical Deposition) method and an MBE (Molecular Beam Epitaxy) method.

  Next, a mask layer (not shown) is formed on the buffer layer 22. The mask layer is, for example, a silicon oxide layer, a titanium oxide layer, a titanium layer, or a laminated film thereof. The mask layer is formed by, for example, film formation by an electron beam vapor deposition method or a plasma CVD (Chemical Vapor Deposition) method, and patterning by a photolithography technique and an etching technique.

  As shown in FIG. 1, the first semiconductor layer 40, the active layer 42, and the second semiconductor layer 44 are epitaxially grown in this order by the MOCVD method, the MBE method, or the like using the mask layer as a mask. Thereby, the 1st columnar part 30 and the 2nd columnar part 32 can be formed. The diameters of the columnar portions 30 and 32 can be adjusted by, for example, the growth temperature of each layer. For example, since the second semiconductor layer 44 is doped with Mg, the diameter tends to be large.

  Next, the first electrode 50 is formed on the buffer layer 22, and the second electrode 52 is formed on the second semiconductor layer 44. For example, before the first electrode 50 is formed, a part of the buffer layer 22 may be etched to form a recess, and the first electrode 50 may be formed in the recess. The first electrode 50 and the second electrode 52 are formed by, for example, a vacuum evaporation method. The order of forming the first electrode 50 and the second electrode 52 is not particularly limited.

  Through the above steps, the light emitting device 100 can be manufactured.

1.3. Modified example of light emitting device 1.3.1. First Modification Next, a light-emitting device according to a first modification of the first embodiment will be described with reference to the drawings. FIG. 8 is a cross-sectional view schematically showing a light emitting device 110 according to a first modification of the first embodiment.

Hereinafter, in the light emitting device 110 according to the first modification of the first embodiment, members having the same functions as those of the components of the light emitting device 100 described above are denoted by the same reference numerals, and detailed description thereof is omitted. This is the same in the light emitting device according to the second modification of the first embodiment described below.

  In the light emitting device 100 described above, as illustrated in FIG. 1, the second semiconductor layers 44 of the plurality of first columnar portions 30 and the second semiconductor layers 44 of the plurality of second columnar portions 32 are separated from each other.

  On the other hand, in the light emitting device 110, as shown in FIG. 8, the second semiconductor layers 44 of the plurality of first columnar portions 30 and the second semiconductor layers 44 of the plurality of second columnar portions 32 are continuous with each other. Yes.

  The light emitting device 110 can have the same effect as the light emitting device 100.

  Further, in the light emitting device 100, the second semiconductor layers 44 of the plurality of first columnar portions 30 and the second semiconductor layers 44 of the plurality of second columnar portions 32 are continuous with each other, so that the second electrode 52 is adjacent. It is possible to suppress entering between the matching second semiconductor layers 44.

1.3.2. Second Modified Example Next, a light emitting device according to a second modified example of the first embodiment will be described with reference to the drawings. FIG. 9 is a plan view schematically showing a light emitting device 120 according to a second modification of the first embodiment. For convenience, the second semiconductor layer 44 and the second electrode 52 are not shown in FIG.

  In the light emitting device 100 described above, as shown in FIG. 2, the first region 2 surrounds the second region 4 in plan view.

  On the other hand, in the light emitting device 120, as shown in FIG. 9, two first regions 2 are provided, and the second region 4 is provided between the two first regions 2 in plan view. .

  The light emitting device 110 can have the same effect as the light emitting device 100.

  Furthermore, in the light emitting device 100, the second region 4 is provided between the two first regions 2 in a plan view, and therefore the light generated in the active layer 42 of the second columnar portion 32 is not seen in the plan view. Laser oscillation can be performed by multiple reflection between the two first regions 2.

2. Second Embodiment 2.1. Next, a light emitting device according to a second embodiment will be described with reference to the drawings. FIG. 10 is a cross-sectional view schematically showing the light emitting device 200 according to the second embodiment.

  Hereinafter, in the light emitting device 200 according to the second embodiment, members having the same functions as the constituent members of the light emitting device 100 described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the light emitting device 100 described above, the second electrode 52 is provided above the second region 4 as shown in FIG.

  On the other hand, in the light emitting device 200, the second electrode 52 is provided above the first region 2 as shown in FIG. 10. The second electrode 52 is provided with an opening 54. The opening 54 overlaps the second columnar part 32 in plan view. The opening 54 is provided above the second region 4. The planar shape of the second electrode 52 is, for example, a ring shape. The second electrode 52 may not be a transparent electrode that transmits light generated in the active layer 42. The second electrode 52 may be made of a material that absorbs light generated in the active layer 42.

  In the illustrated example, the second semiconductor layers 44 of the plurality of first columnar portions 30 and the second semiconductor layers 44 of the plurality of second columnar portions 32 are continuous with each other. Note that the second semiconductor layers 44 of the plurality of first columnar portions 30 and the second semiconductor layers 44 of the plurality of second columnar portions 32 may be separated from each other.

  The light emitting device 200 can have the same effect as the light emitting device 100.

  Further, in the light emitting device 200, the second electrode 52 is provided with an opening 54, and the opening 54 overlaps the second columnar part 32 in plan view. Therefore, in the light emitting device 200, the light generated in the active layer 42 of the second columnar portion 32 can be suppressed from being absorbed by the second electrode 52. Furthermore, in the light emitting device 200, the degree of freedom of the material of the second electrode 52 can be increased.

2.2. Method for Manufacturing Light-Emitting Device Next, a method for manufacturing the light-emitting device 200 according to the second embodiment will be described. The manufacturing method of the light emitting device 200 according to the second embodiment is basically the same as the manufacturing method of the light emitting device 100 described above. Therefore, the detailed description is abbreviate | omitted.

2.3. Next, a light emitting device according to a modified example of the second embodiment will be described with reference to the drawings. FIG. 11 is a cross-sectional view schematically showing a light emitting device 210 according to a modification of the second embodiment.

  Hereinafter, in the light emitting device 210 according to the modified example of the second embodiment, members having the same functions as the constituent members of the light emitting devices 100 and 200 described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  The light emitting device 210 is different from the light emitting device 100 described above in that the stacked body 20 includes a first mirror layer 212 and a second mirror layer 214 that sandwich the second columnar portion 32.

  For example, the first mirror layer 212 is provided between the buffer layer 22 and the support layer 24. The support layer 24 is provided between the first mirror layer 212 and the substrate 10. The support layer 24 is, for example, a GaN layer.

  The second mirror layer 214 is provided on the second semiconductor layer 44. In the illustrated example, the second mirror layer 214 is provided above the second columnar portion 32 (above the second region 4). The second mirror layer 214 is provided in the opening 54 in plan view. The second mirror layer 214 is provided apart from the second electrode 52.

The first mirror layer 212 and the second mirror layer 214 are distributed Bragg reflection type (DBR) mirrors in which a high refractive index layer and a low refractive index layer having a lower refractive index than the high refractive index layer are alternately stacked. is there. The high refractive index layer of the first mirror layer 212 is, for example, a GaN layer. The low refractive index layer of the first mirror layer 212 is, for example, an AlGaN layer, an AlN layer, an InAlN layer, or the like. The high refractive index layer of the second mirror layer 214 is, for example, a Ta ₂ O ₅ layer, a TiO ₂ layer, an HfO ₂ layer, or the like. The low refractive index layer of the second mirror layer 214 is, for example, a SiO ₂ layer. The number of stacked layers (number of pairs) of the high refractive index layer and the low refractive index layer is, for example, 3 pairs or more and 100 pairs or less.

  The first mirror layer 212, the second mirror layer 214, and the support layer 24 are formed by, for example, epitaxial growth using a MOCVD method or MBE method, a vacuum deposition method, a sputtering method, or the like.

  The light emitting device 210 can have the same effect as the light emitting device 200.

  Further, in the light emitting device 210, the stacked body 20 includes a first mirror layer 212 and a second mirror layer 214 that sandwich the second columnar portion 32. Therefore, in the light emitting device 210, the light generated in the active layer 42 of the second columnar section 32 can be laser-oscillated by multiple reflection between the first mirror layer 212 and the second mirror layer 214.

  Further, in the light emitting device 210, the resistance in the stacking direction of the first columnar section 30 is sufficiently larger than the resistance in the stacking direction of the second columnar section 32, so the second columnar section 32 is provided below the second electrode 52. Even if not, the current can be concentrated on the second columnar portion 32.

3. Third Embodiment Next, a projector according to a third embodiment will be described with reference to the drawings. FIG. 12 is a diagram schematically illustrating a projector 900 according to the third embodiment.

  The projector according to the present invention includes the light emitting device according to the present invention. Hereinafter, a projector 900 including the light emitting device 100 as the light emitting device according to the present invention will be described.

  The projector 900 includes a housing (not shown), and a red light source 100R, a green light source 100G, and a blue light source 100B that emit red light, green light, and blue light, respectively, provided in the housing. Each of the red light source 100R, the green light source 100G, and the blue light source 100B includes, for example, a plurality of light emitting devices 100 arranged in an array in a direction orthogonal to the stacking direction, and the base 10 is used as a common substrate in the plurality of light emitting devices 100. Is. The number of the light emitting devices 100 constituting each of the light sources 100R, 100G, and 100B is not particularly limited. For the sake of convenience, in FIG. 12, the casing constituting the projector 900 is omitted, and the light sources 100R, 100G, and 100B are simplified.

  The projector 900 further includes lens arrays 902R, 902G, and 902B, transmissive liquid crystal light valves (light modulation devices) 904R, 904G, and 904B, and a projection lens (projection device) 908 provided in the housing.

  Light emitted from the light sources 100R, 100G, and 100B is incident on the lens arrays 902R, 902G, and 902B. Light emitted from the light sources 100R, 100G, and 100B is collected by the lens arrays 902R, 902G, and 902B, and can be superimposed (partially superimposed), for example. Thereby, the liquid crystal light valves 904R, 904G, and 904B can be irradiated with good uniformity.

  The light condensed by the lens arrays 902R, 902G, and 902B is incident on the liquid crystal light valves 904R, 904G, and 904B. Each of the liquid crystal light valves 904R, 904G, and 904B modulates incident light according to image information. The projection lens 908 enlarges and projects an image (image) formed by the liquid crystal light valves 904R, 904G, and 904B onto a screen (display surface) 910.

  In addition, the projector 900 can include a cross dichroic prism (color light combining unit) 906 that combines light emitted from the liquid crystal light valves 904R, 904G, and 904B and guides the light to the projection lens 908.

The three color lights modulated by the liquid crystal light valves 904R, 904G, and 904B are incident on the cross dichroic prism 906. This prism is formed by bonding four right-angle prisms, and a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are arranged in a cross shape on the inner surface thereof. These dielectric multilayer films combine the three color lights to form light representing a color image. The synthesized light is projected onto the screen 910 by the projection lens 908 which is a projection optical system, and an enlarged image is displayed.

  The light sources 100R, 100G, and 100B control the liquid crystal light valves 904R, 904G, and 904B by controlling (modulating) the light emitting devices 100 constituting the light sources 100R, 100G, and 100B as image pixels according to image information. You may form an image | video directly, without using. The projection lens 908 may enlarge and project the image formed by the light sources 100R, 100G, and 100B onto the screen 910.

  In the above example, a transmissive liquid crystal light valve is used as the light modulation device. However, a light valve other than liquid crystal may be used, or a reflective light valve may be used. Examples of such a light valve include a reflection type liquid crystal light valve and a digital micromirror device (Digital Micromirror Device). Further, the configuration of the projection optical system is appropriately changed depending on the type of light valve used.

Further, the light source 100R, 100G, 100B has scanning means that is an image forming apparatus that displays an image of a desired size on the display surface by causing the light from the light source 100R, 100G, 100B to scan on the screen. The present invention can also be applied to a light source device of a simple scanning image display device (projector).
Applications of the light-emitting device according to the present invention are not limited to the above-described embodiments, but besides projectors, indoor / outdoor lighting, display backlights, laser printers, scanners, in-vehicle lights, sensing devices using light, communication It can also be used as a light source for equipment and the like.

  In the present invention, a part of the configuration may be omitted within a range having the characteristics and effects described in the present application, or each embodiment or modification may be combined.

  The present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same functions, methods, and results, or configurations that have the same objects and effects). In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that exhibits the same operational effects as the configuration described in the embodiment or a configuration that can achieve the same object. Further, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

DESCRIPTION OF SYMBOLS 2 ... 1st area | region, 4 ... 2nd area | region, 6 ... 3rd area | region, 10 ... Base | substrate, 20 ... Laminated body, 22 ... Buffer layer, 24 ... Support layer, 30 ... 1st columnar part, 32 ... 2nd columnar part 34 ... Depletion layer region, 36 ... Non-depletion layer region, 40 ... First semiconductor layer, 42 ... Active layer, 44 ... Second semiconductor layer, 50 ... First electrode, 52 ... Second electrode, 54 ... Opening, DESCRIPTION OF SYMBOLS 100 ... Light-emitting device, 100R, 100G, 100B ... Light source, 110, 200, 210 ... Light-emitting device, 212 ... 1st mirror layer, 214 ... 2nd mirror layer, 900 ... Projector, 902R, 902G, 902B ... Lens array, 904R , 904G, 904B ... Liquid crystal light valve, 906 ... Cross dichroic prism, 908 ... Projection lens, 910 ... Screen

Claims (8)

A substrate;
A laminate provided on the substrate;
Have
The laminate includes a plurality of first columnar portions and second columnar portions,
The minimum diameter of the first columnar part is the length of the depletion layer region in the radial direction of the first columnar part,
The minimum diameter of the second columnar part is a light-emitting device that is larger than the length of the depletion layer region in the radial direction of the second columnar part. In claim 1,
The laminate is
A first region provided with the first columnar part;
A second region provided with the second columnar portion;
Have
The light emitting device, wherein the first region surrounds the second region when viewed from the stacking direction of the stacked body. In claim 1,
The laminate is
A first region provided with the first columnar part;
A second region provided with the second columnar portion;
Have
Two first regions are provided,
The second region is a light emitting device provided between the two first regions when viewed from the stacking direction of the stacked body. In any one of Claims 1 thru | or 3,
Having an electrode provided on the side opposite to the substrate side of the laminate,
The electrode is provided with an opening,
The opening is overlapped with the second columnar portion when viewed from the stacking direction of the stacked body. In any one of Claims 1 thru | or 4,
The stacked body includes a first mirror layer and a second mirror layer sandwiching the second columnar part. In any one of Claims 1 thru | or 5,
The light emitting device is provided with a plurality of the second columnar portions. In claim 6,
The light emitting device, wherein an interval between the adjacent first columnar portions is larger than an interval between the adjacent second columnar portions.   A projector comprising the light emitting device according to claim 1.

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