Nitride Semiconductor Light-Emitting Device with V Pit Generation Layer
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Solution Overview
Problem
Nitride semiconductor light-emitting devices experience deterioration in light emission efficiency when driven under high temperature or at large currents, leading to reduced power efficiency.
Innovation Solution
The device incorporates a V pit generation layer with a higher n-type doping concentration and a superlattice intermediate layer, where the V pits are formed in the multiple quantum well light-emitting layer, with the average starting position of the V pits located in the intermediate layer, to prevent non-light-emitting recombination and enhance power efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a nitride semiconductor light-emitting device is driven under high temperature or at large current, then the output power is increased, but the light emission efficiency deteriorates
Solution Approach 1:
The patent converts the harmful effect of threading dislocations (which cause non-radiative recombination and reduce efficiency) into a beneficial feature by using V-pits to confine carriers. The dislocations that would normally harm performance are instead used to nucleate V-pits, which then serve to prevent carriers from reaching harmful deep-level defects while maintaining high current and temperature operation
Solution Approach 2:
The patent introduces V-pits with specific geometric characteristics (apical angle of 56°, particular depth and width ratios) at specific locations within the active layer to create localized regions with enhanced carrier confinement. This local structural modification optimizes the light emission efficiency in critical regions without affecting the entire device structure
2Loss of energy
If V pits are formed in the multiple quantum well light-emitting layer, then non-light-emitting recombination is suppressed, but the device structure becomes more complex
Solution Approach 1:
The V-pits are formed during the growth process itself by controlling the nucleation conditions in the active layer, rather than adding a separate post-processing step. This preliminary formation of V-pits during MOCVD growth integrates the defect management function into the manufacturing process, reducing overall device complexity
Solution Approach 2:
The patent controls the formation of V-pits by adjusting growth parameters (temperature, composition, doping concentration) during the MOCVD process. By changing these parameters, V-pits are naturally formed with the desired characteristics without requiring additional fabrication steps, thus suppressing non-light-emitting recombination while maintaining manufacturing simplicity
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
This configuration effectively suppresses the deterioration of light emission efficiency at high temperatures and large currents, maintaining high power efficiency by preventing non-light-emitting recombination and increasing the volume of the light-emitting layer contributing to emission.
Implementation Method 1
When a voltage is applied, an electron and a hole are recombined in a well layer in the light-emitting layer, and as a result, light is generated.
Implementation Method 2
when a V pit exists in a MQW light-emitting layer, a quantum well width in the slant surface of the V pit is narrow. Therefore, an electron or a hole injected into the quantum well is prevented from reaching a threading dislocation which is a crystal defect inside the V pit, and as a result, non-light-emitting recombination in the MQW light-emitting layer is suppressed.
Data Source
AI summary
A nitride semiconductor light-emitting device includes an n-type nitride semiconductor layer, a V pit generation layer, an intermediate layer, a multiple quantum well light-emitting layer, and a p-type nitride semiconductor layer provided in this order. The multiple quantum well light-emitting layer is a layer formed by alternately stacking a barrier layer and a well layer having a bandgap energy smaller than that of the barrier layer. A V pit is partly formed in the multiple quantum well light-emitting layer, and an average position of starting point of the V pit is located in the intermediate layer.