Indirect Bandgap Semiconductor Light Emitter with Heterojunction Electron Supply
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Solution Overview
Problem
Conventional electroluminescence devices using direct bandgap semiconductors face high manufacturing costs and integration challenges with silicon substrates, as silicon, an indirect bandgap semiconductor, limits direct electron transitions due to its energy band structure.
Innovation Solution
An electroluminescence device is developed using an indirect bandgap semiconductor layer with a local conduction-band minimum at the Γ-point, combined with a direct bandgap semiconductor layer in a heterojunction, allowing electrons to be supplied to the Γ-valley for efficient light emission at room temperature, reducing fabrication costs and enabling integration with circuit elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If direct bandgap semiconductors are used to form light emitting layers, then light emission efficiency is improved, but manufacturing cost increases and integration with silicon substrates becomes difficult
Solution Approach 1:
The patent introduces an indirect bandgap semiconductor layer as an intermediary between the direct bandgap semiconductor light emitting layer and the silicon substrate. This intermediary layer has a lattice constant intermediate between the direct bandgap semiconductor and silicon, serving as a buffer that reduces lattice mismatch and enables integration while maintaining the light emission properties of the direct bandgap material
Solution Approach 2:
The patent creates a composite semiconductor structure consisting of multiple layers with different bandgap characteristics and lattice constants. The structure combines direct bandgap semiconductor (for light emission), indirect bandgap semiconductor (for lattice matching), and silicon substrate, forming a composite material system that achieves both efficient light emission and ease of manufacture
2Ease of manufacture
If silicon substrate is used for integration, then ease of manufacture is improved, but direct electron transitions are limited due to indirect bandgap structure
Solution Approach 1:
The patent segments the semiconductor structure into distinct functional layers: a silicon substrate for integration, an indirect bandgap semiconductor layer for lattice matching, and a direct bandgap semiconductor layer for efficient electron transitions and light emission. This segmentation allows each layer to perform its optimal function without compromise
Solution Approach 2:
The indirect bandgap semiconductor layer acts as an intermediary that bridges the silicon substrate and the direct bandgap light emitting layer, enabling the system to benefit from both silicon's manufacturing advantages and direct bandgap materials' efficient electron transitions
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 approach allows the use of indirect bandgap semiconductors like silicon and germanium as light emitting layers, reducing fabrication costs and enabling integration with silicon-based circuit elements, while achieving efficient light emission by recombining electrons with holes at the valence band maximum.
Implementation Method 1
electroluminescence devices using indirect bandgap semiconductors
Implementation Method 2
a direct bandgap semiconductor layer formed by a heterojunction on the indirect bandgap semiconductor layer for supplying electrons to the Γ-valley
Data Source
AI summary
This invention provides an electroluminescence device comprising an indirect bandgap semiconductor layer, such as silicon or germanium, having a local conduction-band minimum at the Γ-point in an E-k diagram for using as a light emitting layer, and a direct bandgap semiconductor layer formed by a heterojunction on the indirect bandgap semiconductor layer for using as an electron supply means transporting electrons from a Γ-valley to a Γ-valley when a forward-biased voltage is applied, wherein a light emission is occurred by recombining the electrons transported to the Γ-valley of the indirect bandgap semiconductor layer with holes located at a valance band maximum of the indirect bandgap semiconductor layer.