In the 1980s, Professor Wang Dejun of Jilin University introduced the surface photovoltage method into the research of photochemistry and photocatalysis, and then used this technology to study the behavior of photogenerated charges in materials with semiconductor properties in detail.
Surface Photovoltaic (SPV) Technology
Surface Photovoltaic (SPV) technology is a non-contact measurement method, which can measure the voltage change on the semiconductor surface after illumination with high sensitivity.
In recent years, surface photovoltage technology has been widely used in research fields such as photo-splitting water for hydrogen production, solar cells, photocatalytic degradation, photoelectrosensitivity, and photoelectrochemical water oxidation. The kinetic behavior of photogenerated charges in the corresponding reaction process, and in-depth understanding of the separation, transport and recombination process of photogenerated charges in semiconductors.
Surface photovoltage technology can be used to determine semiconductor conductivity type, measure minority carrier diffusion distance, surface state parameter determination and photogenerated charge behavior, and can also provide charge transition properties, defect states, heterojunction charge transfer, quantum size of semiconductor materials effects, quantum confinement properties, separation, transport and recombination of photogenerated charges.
Surface photovoltage mainly includes steady-state surface photovoltage and transient surface photovoltage.
Steady-state surface photovoltage test
The steady-state surface photovoltage test is based on a lock-in amplifier. As shown in Figure 1, important parameters such as the conductivity type, band gap, and separation efficiency of photogenerated charge carriers at the surface/interface can be obtained.
Figure 1. Schematic diagram of steady-state surface photovoltage spectrometer
Transient Surface Photovoltaic Test
The transient surface photovoltage test is a test system based on the steady state surface photovoltage, using a pulsed laser as the light source, as shown in Figure 2, which can not only reflect the separation efficiency of photogenerated charge carriers in the material, but also effectively The microscopic kinetic information and charge transport capability of the photogenerated charge carrier separation of the material are obtained.
Figure 2. Schematic diagram of transient surface photovoltage spectrometer
Figure 3. Photo of the laboratory site of the surface photovoltage spectrometer
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