Nanocrystal Array Laser Structure for Low-Threshold AR/VR Displays

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Solution Overview

Problem

Micro-LEDs used in AR/VR displays face challenges with high non-radiative recombination, reduced luminous efficiency, and wide beam divergence angles, which affect brightness, resolution, and image quality, and traditional VCSELs with DBR face issues of high threshold voltage and lattice dislocation.

Innovation Solution

A laser device incorporating a silicon-based field effect transistor with a nanocrystal array of gallium nitride nanorods, which reduces lattice dislocation, improves doping efficiency, and adjusts laser wavelength and emission direction through selective growth and structural design, eliminating the need for a DBR.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If traditional VCSEL with DBR is used, then high reflectivity is achieved, but threshold voltage increases and current conductivity decreases

Engineering Contradiction:

ImprovereflectivityVSAvoidthreshold voltage

Core Design Contradiction:

Illumination intensityVSUse of energy by moving object

Solution Approach 1:

The patent extracts and removes the DBR structure from the VCSEL device, replacing it with a nanocrystal array that provides reflectivity without the high impedance characteristics of traditional DBR, thereby reducing threshold voltage and improving current conductivity

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent uses a composite structure combining nanocrystals with the VCSEL active region, where the nanocrystal array provides optical feedback and reflectivity while maintaining low electrical impedance, achieving both high reflectivity and low threshold voltage through material composition optimization

Inventive Principle:

Principle #40Composite materials

2Manufacturing precision

If micro-LED size is decreased, then resolution and pixel density improve, but non-radiative recombination increases and luminous efficiency decreases

Engineering Contradiction:

ImproveresolutionVSAvoidluminous efficiency

Core Design Contradiction:

Manufacturing precisionVSLoss of energy

Solution Approach 1:

The patent changes the physical parameters of the light-emitting structure by using nanoscale crystal dimensions and specific aspect ratios that enhance radiative recombination efficiency, maintaining high luminous efficiency even at reduced device sizes for improved resolution

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent optimizes the local quality of the active region by controlling nanocrystal orientation, size distribution, and spatial arrangement, creating localized high-efficiency emission regions that maintain overall device performance at smaller dimensions

Inventive Principle:

Principle #3Local quality

3Shape

If micro-LED divergence angle is reduced, then beam directionality improves, but pixel spacing cannot be reduced further

Engineering Contradiction:

Improvebeam divergence angleVSAvoidpixel spacing

Core Design Contradiction:

ShapeVSLength of moving object

Solution Approach 1:

The patent transitions from planar micro-LED emission to vertically oriented nanocrystal array emission, utilizing the vertical dimension to achieve narrow beam divergence while maintaining compact lateral pixel spacing, effectively decoupling beam directionality from pixel pitch constraints

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

4Illumination intensity

If group III nitride materials are used for DBR, then high reflectivity is achieved, but lattice dislocation and polarization field increase

Engineering Contradiction:

ImprovereflectivityVSAvoidcrystal structure quality

Core Design Contradiction:

Illumination intensityVSStability of the object's composition

Solution Approach 1:

The patent replaces the complex multi-layer group III nitride DBR structure with a simpler nanocrystal array that achieves comparable or superior reflectivity without inducing lattice dislocation or polarization fields, effectively substituting a problematic structure with a more stable alternative

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enhances luminous efficiency, reduces beam divergence, and improves image quality and resolution by controlling the nanorod structure and arrangement, while reducing power consumption and threshold current.

Implementation Method 1

reduces lattice dislocation, improves doping efficiency

Methodology Applied

Scientific EffectLattice dislocation:

Implementation Method 2

reduces beam divergence, adjusts laser wavelength and emission direction

Methodology Applied

Scientific EffectBeam divergence control:

Implementation Method 3

laser device incorporating a silicon-based field effect transistor with a nanocrystal array

Methodology Applied

Scientific EffectLaser emission: Laser

Data Source

PatentUS20230369828A1Nanocrystal array, laser device, and display device

Publication Date: 2023.11.16 HON HAI PRECISION INDUSTRY CO LTD

AI summary

A nanocrystal array, a laser device, and a display device are provided. The nanocrystal array includes a plurality of nanorods arranged in an array. Each nanorod includes a nanorod buffer layer, a first type semiconductor layer, a tunnel junction layer, a second type semiconductor layer, a multi-quantum well, and another first type semiconductor layer successively stacked on each other. The laser device and the display device include the nanocrystal array. The present disclosure may reduce the laser threshold and increase output power, and further improve the resolution and image quality of the display device.