Vertical Multi-Junction SST Structure for High-Voltage Current Spreading
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Solution Overview
Problem
Conventional high-voltage LEDs and solid-state transducers (SSTs) face performance limitations due to poor current spreading, thermal characteristics, and overall efficiency, particularly when operating with high-voltage power supplies.
Innovation Solution
The development of multi-junction SST devices with buried contacts and vertical configurations, which enhance current spreading and light extraction by using N-type GaN for improved current distribution and thermal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional lateral LED configurations are used, then manufacturing is simpler, but current spreading is poor and efficiency is reduced
Solution Approach 1:
The patent inverts the conventional lateral LED configuration by using vertical LED structures where the light propagation direction is perpendicular to the substrate. This inversion allows N-type GaN to be positioned at the front surface, enabling superior current spreading from the contact through the active region, while maintaining manufacturing feasibility through established vertical growth techniques.
Solution Approach 2:
The patent transitions from a lateral (in-plane) current spreading geometry to a vertical (out-of-plane) current spreading geometry. This dimensional change allows the current to spread through the thickness of the device rather than laterally across the surface, fundamentally improving current distribution and efficiency while enabling new structural configurations.
2Device complexity
If conventional lateral LED configurations are used, then device structure is simpler, but thermal characteristics are poor
Solution Approach 1:
The patent inverts the thermal management approach by positioning the N-type GaN contact at the front surface, allowing heat to be conducted directly from the active region through the N-type GaN layer to the substrate. This vertical thermal pathway is more efficient than lateral heat dissipation in conventional structures, improving thermal characteristics while managing device complexity.
3Loss of energy
If high-voltage LEDs are used with high-voltage power supplies, then system efficiency is improved, but voltage matching with standard power supplies is difficult
Solution Approach 1:
The patent segments the LED device into multiple series-connected junctions within a single vertical structure, enabling the device to operate at high voltages (e.g., 60V) that match standard power supplies. This segmentation approach allows direct connection to mains power without complex voltage conversion, improving both system efficiency and power supply compatibility simultaneously.
4Productivity
If N-type GaN is used at the front surface for improved current spreading, then current distribution is enhanced, but contact transparency may be reduced
Solution Approach 1:
The patent applies local quality by making the N-type GaN contact region selectively transparent or semi-transparent in the active emission area while maintaining electrical conductivity. This allows the contact to perform its current spreading function while minimizing interference with light extraction, achieving both improved current distribution and maintained illumination intensity through localized material property optimization.
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
These high-voltage SST devices achieve increased efficiency and performance by reducing the voltage difference across power supply components, allowing for direct driving by standard AC power supplies and improving thermal performance.
Implementation Method 1
using N-type GaN for improved current distribution
Implementation Method 2
light-emitting diodes (LEDs)...utilize light-emitting diodes for backlighting
Implementation Method 3
gallium nitride/indium gallium nitride (GaN/InGaN) multiple quantum wells (MQWs)
Implementation Method 4
enhance current spreading and light extraction by using N-type GaN for improved current distribution and thermal management
Data Source
AI summary
High-voltage solid-state transducer (SST) devices and associated systems and methods are disclosed herein. An SST device in accordance with a particular embodiment of the present technology includes a carrier substrate, a first terminal, a second terminal and a plurality of SST dies connected in series between the first and second terminals. The individual SST dies can include a transducer structure having a p-n junction, a first contact and a second contact. The transducer structure forms a boundary between a first region and a second region with the carrier substrate being in the first region. The first and second terminals can be configured to receive an output voltage and each SST die can have a forward junction voltage less than the output voltage.