What was the revenue generated by AXT in Q3 2021 for indium phosphide and gallium arsenide 
mands and our ability to expand capacity to meet customer demand is beginning to open up new avenues of opportunities in multiple applications.
Of our peers, we believe that we are in the best position to be able to respond. In Q3, indium phosphide and sequential growth were driven by 4G and 5G telecommunication obligations as well as continued healthcare -- healthy demand for data center connectivity. We believe that these applications are closely related and as the exponential growth in data necessities, both the infrastructure to move it as well as our capability to efficiently handle and store it. From a substrate perspective, any modernization of telecom and datacom center infrastructure that utilizes indium phosphide is positive for our business whether that's PONs, fronthaul or backhaul infrastructure or silicon photonics buildout that's within the data center.
While there will be -- continue to be quarter-to-quarter fluctuations, we believe that we have reached a tipping point in which the application that will require indium phosphide have become an essential part of modernization of telecommunications business. And in addition to these major applications, we believe there are significant new applications for indium phosphide now visible on the horizon in healthcare monitoring, automotive sensors, and more. Among the AXT's competitive advantage in indium phosphide is our ability to scale manufacturing volume quickly and efficiently to meet rising demand. In addition, we have been told by multiple customers that our VGF raw material uniformity as well as consistently provide the industry lowest EPD level, which are an essential requirement for high-performance applications in Tier 1 specifications.
Now turning to indium -- gallium arsenide. In Q3, we posted our highest quarterly revenue in more than four years. In our semiconductor gallium arsenide, we continue to see strong demand for high-end LED applications, including automotive and lighting and display. We are also seeing rapid growth in high-powered lasers, particularly in China.
On wireless side, IoT continues to be that strong. In addition, with 6-inch capacity tightening up in our industry, we're beginning to see demand from customers -- from -- renewed customer demand interest in gallium arsenide for HBT devices and our ability to expand capacity. This has not been a strong application for us for many -- more than 10 years, and our facilities give us the opportunity to be competitive and when stocked. As we look ahead to the evolution of gallium arsenide in high-tech applications, we believe micro LED, in particular, hold great promises for our industry.
Major customer device manufacturers are behind the development of the technology for a variety of our applications, including televisions, AR-VR headsets and portable devices and others. Micro LEDs, which should not be confused with mini LEDs, uses gallium arsenide to make red, for the red, blue green led modules that we can provide almost any color. Micro LED devices are expected to consume less power, provide sharper contrasts, and produce brilliant lighting and colors. We're seeing reports that the potential micro LED market for smaller consumer devices like wearables and phones could be larger than the entire current market for gallium arsenide substrate today.
Regardless of the specific numbers, this is an exciting space and could add significantly new value to the LED market in 2024 and beyond. Now turning to R&D. We continue to progress on the development of 8-inch gallium arsenide wafers. Among the many benefits to our customers, 8-inch gallium arsenide will help to enable -- to scale and cost effectively, which is required for very high-volume applications.
And as you know, every step up in diameter size comes with a major increase in the technical challenges of producing it but we have successfully delivered sample quantities to interested customers and we are working with them to meet the requirement of their emerging projects. Moving now to germanium substrates. Revenue have decreased modest
mands and our ability to expand capacity to meet customer demand is beginning to open up new avenues of opportunities in multiple applications.
Of our peers, we believe that we are in the best position to be able to respond. In Q3, indium phosphide and sequential growth were driven by 4G and 5G telecommunication obligations as well as continued healthcare -- healthy demand for data center connectivity. We believe that these applications are closely related and as the exponential growth in data necessities, both the infrastructure to move it as well as our capability to efficiently handle and store it. From a substrate perspective, any modernization of telecom and datacom center infrastructure that utilizes indium phosphide is positive for our business whether that's PONs, fronthaul or backhaul infrastructure or silicon photonics buildout that's within the data center.
While there will be -- continue to be quarter-to-quarter fluctuations, we believe that we have reached a tipping point in which the application that will require indium phosphide have become an essential part of modernization of telecommunications business. And in addition to these major applications, we believe there are significant new applications for indium phosphide now visible on the horizon in healthcare monitoring, automotive sensors, and more. Among the AXT's competitive advantage in indium phosphide is our ability to scale manufacturing volume quickly and efficiently to meet rising demand. In addition, we have been told by multiple customers that our VGF raw material uniformity as well as consistently provide the industry lowest EPD level, which are an essential requirement for high-performance applications in Tier 1 specifications.
Now turning to indium -- gallium arsenide. In Q3, we posted our highest quarterly revenue in more than four years. In our semiconductor gallium arsenide, we continue to see strong demand for high-end LED applications, including automotive and lighting and display. We are also seeing rapid growth in high-powered lasers, particularly in China.
On wireless side, IoT continues to be that strong. In addition, with 6-inch capacity tightening up in our industry, we're beginning to see demand from customers -- from -- renewed customer demand interest in gallium arsenide for HBT devices and our ability to expand capacity. This has not been a strong application for us for many -- more than 10 years, and our facilities give us the opportunity to be competitive and when stocked. As we look ahead to the evolution of gallium arsenide in high-tech applications, we believe micro LED, in particular, hold great promises for our industry.
 Major customer device manufacturers are behind the development of the technology for a variety of our applications, including televisions, AR-VR headsets and portable devices and others. Micro LEDs, which should not be confused with mini LEDs, uses gallium arsenide to make red, for the red, blue green led modules that we can provide almost any color. Micro LED devices are expected to consume less power, provide sharper contrasts, and produce brilliant lighting and colors. We're seeing reports that the potential micro LED market for smaller consumer devices like wearables and phones could be larger than the entire current market for gallium arsenide substrate today.
Regardless of the specific numbers, this is an exciting space and could add significantly new value to the LED market in 2024 and beyond. Now turning to R&D. We continue to progress on the development of 8-inch gallium arsenide wafers. Among the many benefits to our customers, 8-inch gallium arsenide will help to enable -- to scale and cost effectively, which is required for very high-volume applications.
And as you know, every step up in diameter size comes with a major increase in the technical challenges of producing it but we have successfully delivered sample quantities to interested customers and we are working with them to meet the requirement of their emerging projects. Moving now to germanium substrates. Revenue have decreased modest