Nitride Semiconductor Light Emitting Device Silicon Substrate
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Solution Overview
Problem
Nitride semiconductor light emitting devices using sapphire substrates are costly, have low electrical and thermal conductivities, leading to short device lifetime and limited application in micro-electromechanical systems and micro optoelectronic integrated circuits due to high insulating properties.
Innovation Solution
A nitride semiconductor light emitting device is fabricated using a silicon substrate with a super-lattice buffer layer, comprising multiple conductive clad layers and an active layer, which enhances electrical and optical characteristics and reduces production costs by eliminating lattice defects and allowing for the integration of photoelectric and electronic characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sapphire substrate is used to grow nitride semiconductor, then good quality nitride semiconductor can be obtained, but production cost increases and electrical/thermal conductivities decrease
Solution Approach 1:
The patent changes the substrate material parameter from sapphire to silicon, fundamentally altering the electrical and thermal conductivity properties. This parameter change enables the device to achieve both low cost and improved reliability through silicon's superior electrical conductivity (10^-3 to 10^6 S/cm) and thermal conductivity (1.5 W/cmK) compared to sapphire.
Solution Approach 2:
The patent employs a composite structure consisting of a silicon substrate combined with a buffer layer and nitride semiconductor layers. This composite approach allows the silicon substrate to provide excellent electrical and thermal conductivity while the buffer layer and semiconductor layers maintain the necessary optical and electronic properties for light emission.
2Reliability
If a sapphire substrate is used, then good quality nitride semiconductor can be grown, but heat release becomes insufficient leading to short device lifetime
Solution Approach 1:
The patent changes the thermal conductivity parameter of the substrate from sapphire's low value to silicon's high value (1.5 W/cmK). This parameter change directly improves heat dissipation capability, preventing overheating and extending device lifetime by efficiently conducting heat away from the active region.
3Adaptability or versatility
If a sapphire substrate is used, then photoelectric characteristics can be achieved, but electrical and electronic characteristics cannot be integrated
Solution Approach 1:
The patent changes the electrical conductivity parameter of the substrate from sapphire's high insulating property to silicon's semiconducting property. This fundamental parameter change enables the integration of both photoelectric and electronic characteristics in a single device, expanding application scope to include MEMS and OEIC devices.
Solution Approach 2:
The silicon substrate provides multiple functions simultaneously: it serves as the mechanical support, the electrical conductor, the thermal management component, and the platform for integrating both photoelectric and electronic characteristics. This multi-functionality enables the device to be applied in diverse fields including LEDs, laser diodes, MEMS, and OEICs.
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
The use of a silicon substrate with a super-lattice buffer layer improves the reliability and optical properties of the light emitting device, reduces production costs, and enables the fabrication of devices with combined electrical and electronic characteristics, extending the device's lifetime and application scope.
Implementation Method 1
forming a buffer layer having a super-lattice layer on a silicon substrate
Implementation Method 2
electrons are injected from the n-type clad layer 40 into the active layer 50, and holes are injected from the p-type clad layer 60 into the active layer 50. At this time, the electrons and holes injected into the active layer 50 are recombined to produce light
Data Source
AI summary
Disclosed is a nitride semiconductor light emitting device. The nitride semiconductor light emitting device comprises a buffer layer having a super-lattice layer on a silicon substrate, a first conductive clad layer on the buffer layer, an active layer on the first conductive clad layer, and a second conductive clad layer on the active layer.