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JP-2026075807-A - Vertical resonator type light-emitting element and method for manufacturing a vertical resonator type light-emitting element

JP2026075807AJP 2026075807 AJP2026075807 AJP 2026075807AJP-2026075807-A

Abstract

[Problem] The objective is to provide a vertical resonator type light-emitting element with a low threshold current density and high luminous efficiency, and a method for manufacturing a vertical resonator type light-emitting element. [Solution] The method comprises the steps of forming a first reflector, forming a first semiconductor layer on the first reflector, forming a multiple quantum well layer on the first semiconductor layer including first to n well layers (where n is an integer of 3 or more), forming a final barrier layer on the nth well layer which is the final well layer of the multiple quantum well layer, forming an electron barrier layer on the final barrier layer, forming a second semiconductor layer on the electron barrier layer, and forming a second reflector on the second semiconductor layer. The first to nth well layers have In as their composition and are grown using nitrogen ( N₂ ) as the carrier gas. In the step of forming the final barrier layer, the growth temperature is increased and hydrogen ( H₂ ) is added to the carrier gas during growth. [Selection Diagram] Figure 1

Inventors

  • 倉本 大

Assignees

  • スタンレー電気株式会社

Dates

Publication Date
20260511
Application Date
20241023

Claims (11)

  1. Forming the first reflector, A first semiconductor layer is formed on the first reflector. A multiple quantum well layer is formed on the first semiconductor layer, including first to n well layers (where n is an integer of 3 or more). A final barrier layer is formed on the nth well layer, which is the final well layer of the multiple quantum well layer. An electron barrier layer is formed on the aforementioned final barrier layer, A second semiconductor layer is formed on the electron barrier layer. The process includes a step of forming a second reflector on the second semiconductor layer, The first to n well layers are composed of In and are grown using nitrogen ( N2 ) as the carrier gas. The step of forming the final barrier layer involves increasing the growth temperature and adding hydrogen ( H₂ ) to the carrier gas to carry out the growth. A method for manufacturing a vertical resonator type light-emitting element.
  2. The method for manufacturing a vertical resonator type light-emitting element according to claim 1, wherein the step of forming the final barrier layer is to raise the growth temperature within the range of 25 to 200°C.
  3. The method for manufacturing a vertical resonator type light-emitting element according to claim 1, wherein the step of forming the final barrier layer is to add hydrogen ( H₂ ) to the carrier gas at a hydrogen partial pressure of 10% or more.
  4. When the peak gain wavelengths of the first to nth well layers are denoted as λp(1), ..., λp(n-1), λp(n), the peak gain wavelengths are: λp(1)＜...＜λp(n-1), and λp(1)＜λp(n)＜λp(n-1) Formula (1) A method for manufacturing a vertical resonator type light-emitting element according to any one of claims 1 to 3 that satisfies the requirements.
  5. The method for manufacturing a vertical resonator type light-emitting element according to claim 1, wherein the thickness of the final barrier layer is 40 nm or more.
  6. The method for manufacturing a vertical-cavity light-emitting element according to claim 1, wherein the vertical-cavity light-emitting element is a nitride surface-emitting laser made of a GaN (gallium nitride) semiconductor.
  7. The first reflector, A first semiconductor layer formed on the first reflector, An active layer comprising a multiple quantum well layer formed on the first semiconductor layer and including first to n well layers (n is an integer of 3 or more), and a final barrier layer formed on the nth well layer which is the final well layer of the multiple quantum well layer, An electron barrier layer formed on the final barrier layer, A second semiconductor layer formed on the electron barrier layer, The present invention comprises a second reflector formed on the second semiconductor layer, The first to n well layers have In in their composition. The nth well layer has a lower In composition than the (n-1)th well layer. When the peak gain wavelengths of the first to nth well layers are denoted as λp(1), ..., λp(n-1), λp(n), the peak gain wavelengths are: λp(1)＜...＜λp(n-1), and λp(1)＜λp(n)＜λp(n-1) Formula (1) A vertical resonator type light-emitting element that satisfies the following conditions.
  8. The vertical resonator type light-emitting element according to claim 7, wherein the thickness of the final barrier layer is 40 nm or more.
  9. The aforementioned electron barrier layer contains Al (aluminum), The vertical resonator type light-emitting element according to claim 7, wherein the electron barrier layer comprises a first electron barrier layer and a second electron barrier layer having a lower Al composition than the first electron barrier layer.
  10. The vertical-cavity light-emitting element according to claim 9, wherein the first electron barrier layer is thicker than the second electron barrier layer.
  11. The vertical resonator type light-emitting element is a nitride surface-emitting laser made of a GaN (gallium nitride) semiconductor, as described in any one of claims 7 to 10.

Description

This invention relates to a vertical resonator type light-emitting element and a method for manufacturing a vertical resonator type light-emitting element, particularly a vertical resonator type light-emitting element having a multiple quantum well active layer and a method for manufacturing a vertical resonator type light-emitting element. Conventionally, vertical cavity surface-emitting lasers (VCSELs), which have a structure that resonates light perpendicular to the substrate surface and emits light in a direction perpendicular to the substrate surface, are known as vertical cavity light-emitting devices. In vertical-cavity light-emitting devices, a multiple quantum well (MQW) structure is generally employed in the active layer to achieve low threshold current and high-efficiency light emission characteristics. For example, Patent Document 1 describes an end-face emission nitride semiconductor laser element having a structure aimed at improving internal quantum efficiency by lowering the electron and hole concentrations in the p-side optical guide layer between the final quantum well layer and the electron barrier layer. Furthermore, Patent Documents 2 and 3 describe a mechanism for improving characteristics while considering standing waves in a resonator. Furthermore, Non-Patent Documents 1 and 2 describe the effect known as CPE (Compositional pulling effect) in crystal growth, and the segregation of InGaN/GaN and AlGaN/AlN, respectively. Japanese Patent Publication No. 2014-131019Japanese Patent Publication No. 2024-131244Japanese Patent Publication No. 2023-43084 S. Pereira et al., Physical Review B, vol.64, 205311(2001)B. Liu et al., Applied Physics Letters 98, 261916(2011) This is a schematic cross-sectional view showing the structure of a vertical-cavity surface-emitting laser (VCSEL) according to the first embodiment of the present invention.This diagram schematically shows the band structure of the conduction band of a vertical-cavity surface-emitting laser.This is a flowchart showing a method for manufacturing a vertical cavity surface-emitting laser.This figure schematically shows the gain profile of each quantum well layer and the combined gain profile of a multiple quantum well active layer (CMP) in which all well layers and all barrier layers were grown under the same growth conditions.This figure schematically shows the gain profiles of each quantum well layer and the combined gain profile of the active layer (EMB) of the first embodiment.This figure shows the results of the In composition analysis of the well layers (QW1 to QW4) of the active layer (EMB) of the first embodiment using EDX.This table shows the experimental results of the final barrier layer thickness, average Al composition of the electron barrier layer, and internal quantum efficiency of Examples 1 and 2 of the vertical-cavity surface-emitting laser of this embodiment, in comparison with the experimental results of Comparative Examples 1 and 2.This graph shows the temperature characteristics of Example 1, in which H2 was added to N2 as the carrier gas, and Comparative Example 1, in which N2 was used as the carrier gas. The following describes preferred embodiments of the present invention, which may be modified and combined as appropriate. Furthermore, in the following description and accompanying drawings, substantially identical or equivalent parts are denoted by the same reference numerals. [First Embodiment] (1) Structure of a Vertical Cavity Surface Emitting Laser Figure 1 is a schematic cross-sectional view showing the structure of a vertical cavity surface emitting laser 10 (VCSEL) according to the first embodiment of the present invention. In this embodiment, the vertical cavity surface emitting laser 10 is a nitride surface emitting laser made of a GaN (gallium nitride) semiconductor layer. The vertical-cavity surface-emitting laser 10, a vertical-cavity light-emitting element, is constructed by sequentially forming the following layers on a substrate 11 in this order: a semiconductor DBR (Distributed Bragg Reflector) 12 (first reflector), an n-type semiconductor layer 13 (first semiconductor layer), an active layer 15 consisting of multiple quantum wells, an electron barrier layer (EBL: Electron Blocking Layer) 17, and a p-type semiconductor layer 18 (second semiconductor layer). The active layer 15 is composed of a multiple quantum well layer 15Q and a final barrier layer 15L. Furthermore, the vertical-cavity surface-emitting laser 10 includes an insulating film 21 (current constriction layer) for current and light confinement, formed in the recesses surrounding a p-type semiconductor layer 18 having a circular convex portion; a transparent conductive film 22 provided on the p-type semiconductor layer 18 and the insulating film 21; a spacer layer 24 provided on the transparent conductive film 22; and a dielectric DBR 25 (second reflector) provided on the spacer layer 24. Note that the spacer layer 24 may be omitt