Integrated FET Modulator for Solid-State Lighting
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Solution Overview
Problem
High-powered solid-state lighting sources (SSLS) operating in short-pulse modulated mode face self-heating issues and reliability degradation due to high current density, which external modulators attempt to address but introduce parasitic parameters and increased size, weight, and cost.
Innovation Solution
Integration of a field-effect transistor (FET) modulator within the SSLS device, receiving modulation voltage pulses to control drive current, eliminating parasitic parameters and enabling fast and efficient light modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external modulators are used to address self-heating issues and reliability degradation, then modulation capability is improved, but parasitic parameters increase causing modulation time limitations and optical pulse distortions
Solution Approach 1:
The patent merges the modulator and SSLS into a single integrated device structure. The modulator component is formed within the same semiconductor substrate as the SSLS, eliminating the need for separate external modulator components and their associated parasitic parameters. This integration maintains modulation capability while reducing device complexity and improving reliability.
Solution Approach 2:
The patent extracts the modulator function from external components and embeds it directly within the SSLS structure. By taking out the modulation capability and integrating it at the device level, the patent eliminates parasitic parameters associated with external connections while maintaining the desired modulation performance.
2Ease of operation
If external driver circuits are used for modulation, then modulation control is achieved, but weight and cost of the system increase
Solution Approach 1:
The patent combines the modulation control function directly into the SSLS device structure. The modulator is formed within the same semiconductor substrate, eliminating the need for separate external driver circuits. This integration maintains ease of operation through electrical control while significantly reducing system weight.
3Duration of action of moving object
If external optical modulators are used, then light modulation is achieved, but optical loss and power consumption increase
Solution Approach 1:
The patent merges the optical modulation function directly into the light-generating structure. The modulator is formed within the same semiconductor substrate as the SSLS, allowing direct electrical control of light emission without intermediate optical components. This eliminates optical loss associated with external modulators while maintaining fast modulation speed.
4Power
If high current density is used to achieve high optical output, then optical power is improved, but self-heating issues and reliability degradation occur
Solution Approach 1:
The patent employs periodic pulsed operation of the SSLS device. The integrated modulator enables precise control of current pulses, allowing the device to operate at high current density only during brief pulse durations. This periodic action achieves high optical power output while limiting cumulative heat generation and self-heating effects.
Solution Approach 2:
The patent maintains continuous modulation capability through the integrated modulator structure. The modulator can continuously switch the SSLS between on and off states, enabling sustained pulsed operation that delivers high optical power while managing thermal effects through duty cycle control.
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 reduces self-heating and enhances reliability by allowing short voltage pulses of high current amplitude, achieving faster and more efficient light modulation with reduced thermal impact and increased device lifetime.
Implementation Method 1
a field-effect transistor (FET) modulator having a drain region, a gate electrode, and a source electrode integrated in the SSLS access region between the active p-n junction region and one of the current supply electrodes
Implementation Method 2
an active p-n junction region for electron-hole pair recombination and light emission therefrom
Implementation Method 3
High current flowing through a SSLS can create significant self-heating issues and reliability degradation
Data Source
AI summary
A solid-state light source (SSLS) with an integrated electronic modulator is described. A device can include a SSLS having an active p-n junction region is formed within the SSLS for electron-hole pair recombination and light emission. the active p-n junction region can include a n-type semiconductor layer, a p-type semiconductor layer and a light generating structure formed there between. A pair of current supply electrodes can be formed to receive a drive current from a current supply source that drives the SSLS. A field-effect transistor (FET) modulator can be monolithically integrated with the SSLS for modulation thereof. The FET modulator can receive a modulation voltage from a modulation voltage source. The modulation voltage includes voltage pulses having a pulse amplitude and polarity to turn on and off current flowing through the FET modulator. These voltage pulses enable the FET modulator to control the drive current supplied to the SSLS.