Innovating Infrared Material Testing

Experience unmatched sensitivity with microwave-based lifetime measurements—up to 1000x more effective than traditional TRPL for infrared materials. Unlike light-based methods, our charge-sensing approach excels where IR emission is weak or absent. Whether you’re pushing boundaries in material development or need low-temp or high-temp testing, the 8D Wafer Mapping System adapts to your needs.

The Science

Photo-generated charge alters the microwave reflection coefficient of semiconductor materials. When constructed properly, microwave based lifetime measurements have orders of magnitude more sensitivity than other approaches for infrared materials. In many scientific fields, time-resolved photoluminescence (TRPL) or other light analysis based measurements using visible light are highly successful in quantifying the response dynamics of materials.

There are several key reasons microwave measurements are superior in general to TRPL for infrared devices:

In typical measurements of IR materials, microwave based measurements are 1000x more sensitive than TRPL. Cooled IR detectors used to analyze light in TRPL experiments are not very sensitive compared to detectors in the visible portion of the spectrum where TRPL can be more effective. This enhanced sensitivity translates to greater measurement speed.

Charge vs Photon sensing: To characterize the minority carrier lifetime of a material, the injection level must be below the doping level of the material. This means the injection level for valid measurements, and subsequently the number of PL photons available to measure, is essentially fixed. As your materials improve and lifetimes increase, TRPL suffers from reduced signal levels. Microwave based measurements sensing the charge in the material have no such limitations.

IR materials often don’t emit light well, especially in the material development stages or when growth problems occur. This complicates using light analysis techniques.

Cooled IR detectors with adequate performance for TRPL require liquid nitrogen

No Light, No Problem

It is often the case that research-grade materials emit light with very poor efficiency and Microwave techniques are much greater than 1000x more effective. That said, there can be good reasons for desiring TRPL as a supplement to TMR, depending on your material or application, and these needs can be accommodated in the 8D Wafer Mapping System. Microwave measurements can also be implemented to replace many light-analysis techniques for material characterization, not just lifetime measurements. If you are unsure about what approach will work for you, we are happy to discuss. It is also worth noting that while we specialize in low temperature measurement systems, high temperatures are not a problem if that is needed for your application.