Material Properties and Applications of Gallium Arsenide (GaAs)
Gallium Arsenide (GaAs) is a III-V compound semiconductor, and it has a wide band gap a high electron mobility.
• Band Gap : 1.27 eV (300K) (1.2 times that of Si)
• Electron Mobility : 8,500 cm2/Vs (300K) (5.7 times that of Si)
There are a lot of GaAs applications and devices commercially available. First application is radio-frequency (RF) devices and monolithic-microwave-integrated-circuits (MMICs) including power amplifiers, control products and oscillators. These devices have advantages of high speed switching and low noise. Second application is solar cells. The devices show higher efficiency compared to conventional silicon solar cells. Another application is infrared light-emitting-diodes (LEDs) and laser diodes (LDs).
GaAs Pillar Etching for Optoelectronics
GaAs pillar arrays are used for various optoelectronic devices to enhance light output and absorption. For example, the arrays are key parts of light output efficiency enhancement in GaAs-based light emitting diodes (LEDs). The structures are also important to improve conversion efficiency of GaAs-based solar cells. Top-down and bottom-up approaches are available to fabricate the nanopillar structures. Among several fabrication methods, the top-down approach using plasma etching technology offers uniform and precisely controlled structures. GaAs plasma etching recipe needs to be developed to meet each customer’s process demands on shape and geometry of GaAs pillar arrays.
GaAs pillars with high aspect ratio were fabricated using chlorine chemistry. This process is highly repeatable with very low by-product formation.
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Etch Depth : 5 µm
Aspect Ratio : 8.06
Etch Selectivity : 16.6 (over photoresist)
Anisotropic GaAs Etching
Anisotropic GaAs etching was performed using chlorine chemistry, and sidewall angle of 89° was achieved.
Etch Depth : 24 µm
Etch Rate : 1.25 µm/min
Etch Selectivity : 4.2 (over photoresist)
Etch Rate : 2 µm/min
Photo courtesy of University of Delaware
GaAs Etching for Photonic Crystal Fabrication
Photonic crystal fabrication is one of SAMCO’s experienced processes, which are developed in collaboration with customers.
SAMCO offers precise etching technology of various materials including GaAs, InP and silicon to fabricate periodic optical nanostructures.
Photo courtesy of Arakawa/Iwamoto Lab, the University of Tokyo
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GaAs Trench Etching
GaAs trench etching was performed for field-effect-transistor (FET) fabrication.
The etched profile showed smooth and vertical sidewalls.
GaAs Die Separation by Plasma Scribing
With the development of nano-scale products, there is more demand for device miniaturization, especially on RF devices used in smartphones. Also there is more demand for an increase in the number of die per wafer.
SAMCO offers GaAs die separation processes by using Plasma Scribing. Etching is not influenced by the wafer’s crystal orientation of GaAs, and chipping/cracking of dies does not occur. Furthermore, the etched profile shows smooth and vertical sidewalls.
Street Width : 40 μm
Etch Depth : 148 μm
Etch Rate : 3.3 μm/min
Etch Selectivity : 30.7 (over photoresist)
Street Width : 5 μm
Etch Depth : 60 μm
Etch Rate : 1.78 μm/min
Etch Selectivity : 22.3 (over photoresist)
System Lineup for GaAs Dry Etching
ICP Etch Systems
– ICP plasma sources optimizing GaAs etch profile control
– Optional optical/Interferometric end-point detection
– Easy-to-use touch-panel GUI
ICP Etch Systems for Batch Processing
– Process chambers accommodating multiple small wafers
– Optional optical/Interferometric end-point detection
– Easy-to-use touch-panel GUI
Testimonial
SAMCO’s GaAs etching technologies have contributed to manufacturing of LEDs, laser diodes and RF devices.
Also, it is used for device fabrication at laboratories including
