Recombination time is often convinient to measure via microwave reflection e.g. https://www.osti.gov/servlets/purl/1592044

At high excitation one may achive 'quadratic recombination' which gives information regarding minority/majority differences e.g.

https://www.osti.gov/servlets/purl/1419412

Article Quadratic recombination in silicon and its influence on the ...

Also,

https://www.semi.org/sites/semi.org/files/2020-08/AUX017-00-0310E.pdf

https://www.laserfocusworld.com/test-measurement/test-measurement/article/16556318/lightactivated-microwave-method-improves-semiconductor-carrierlifetime-measurement

Dear Kh. N. Juraev,

From what I know, time-resolved photoluminescence spectroscopy is a powerful technique for studying the carriers' lifetime in semiconductors.

The femtosecond or picosecond lasers maybe needed.

Guanghao Qu

Dear Dr. Kh. N. Juraev,

You may want to review information presented below:

The measurement of carrier lifetime in wide bandgap semiconductors typically involves specialized equipment and techniques. Carrier lifetime refers to the average time a charge carrier (electron or hole) exists in a semiconductor material before recombining with an opposite carrier. This parameter is crucial for understanding the charge transport and recombination processes in the material. Here are some common equipment and techniques used for carrier lifetime measurements in wide bandgap semiconductors:

It's important to note that the specific equipment and techniques used can vary based on the desired accuracy, measurement speed, sample properties, and available resources. Researchers often choose the technique that best suits their research goals and the properties of the wide bandgap semiconductor under investigation. Additionally, these techniques might require specialized sample preparation, such as creating suitable contacts and optimizing the sample's surface conditions.

Carrier lifetime is a key parameter in the study of semiconductor materials and devices, as it has a significant influence on device performance in a wide range of applications, from photovoltaics and photodetectors to transistors and LEDs. For wide bandgap semiconductors, which are often used in high-power, high-temperature, and high-frequency applications, accurate measurement of carrier lifetime is particularly critical.

Devices and Techniques for Carrier Lifetime Measurement:

Time-Resolved Photoluminescence (TRPL) Spectroscopy:

Principle: When the semiconductor is optically excited, carriers recombine and emit photoluminescence. By measuring the time decay of the photoluminescence, one can infer the carrier lifetime.

Suitability for Wide Bandgap: Often used for wide bandgap materials.

Minority/Majority/Recombination: Mostly sensitive to radiative recombination processes, which can often involve minority carriers.

Microwave Photoconductivity Decay (μ-PCD):

Principle: A laser pulse generates carriers, and their subsequent recombination causes a change in the microwave reflection coefficient of the sample, which is monitored over time.

Suitability for Wide Bandgap: Quite suitable, especially for materials like SiC and GaN.

Minority/Majority/Recombination: Generally provides information on minority carrier lifetime.

Deep Level Transient Spectroscopy (DLTS):

Principle: It measures the rate at which carriers are emitted from electrically active defects within the semiconductor.

Suitability for Wide Bandgap: Suitable, especially to understand defect levels.

Minority/Majority/Recombination: Sensitive to defects that can act as recombination centers.

Time-Correlated Single Photon Counting (TCSPC):

Principle: Similar to TRPL, but more sensitive. Measures the time between the excitation pulse and the arrival of emitted photons.

Suitability for Wide Bandgap: Suitable.

Minority/Majority/Recombination: Mostly sensitive to radiative recombination processes, which can often involve minority carriers.

Open-Circuit Voltage Decay (OCVD):

Principle: A light pulse is used to generate excess carriers in a device under open-circuit conditions. The subsequent decay in open-circuit voltage is related to carrier recombination.

Suitability for Wide Bandgap: Suitable.

Minority/Majority/Recombination: This can give information about both minority and majority carriers, depending on the setup.

Transient Grating Spectroscopy (TGS):

Principle: A spatially varying excitation pulse (grating) is used to generate carriers, and their spatial and temporal evolution is studied.

Suitability for Wide Bandgap: This can be used, though perhaps less common for wide bandgap materials.

Minority/Majority/Recombination: This can provide insight into diffusion processes, and thereby information on both minority and majority carriers.

Electron Beam Induced Current (EBIC):

Principle: In this technique, an electron beam is used to generate excess carriers locally, and the induced current is measured as a function of time or position.

Suitability for Wide Bandgap: Suitable, but may require specialized setups.

Minority/Majority/Recombination: Provides information on minority carriers.

It's important to note that no single method is likely to provide a complete picture, and a comprehensive study often involves multiple techniques to cross-verify the measured parameters and to gain insights into different types of carrier dynamics (generation, recombination, trapping, etc.).

As an expert in this field, you'd be aware that the choice of technique can depend not just on the material, but also on the specific questions you're trying to answer about carrier dynamics, the quality of the material, the available experimental setup, and so on. Each method has its own limitations and areas where it excels, and your deep understanding of the underlying physics and device applications will guide your choice of the most appropriate methods for your specific research needs.