Semiconductor InAs Wafer for Photo-Dember Effect Study
As a narrow bandgap semiconductor, InAs has a significant difference in electron and hole mobility, which makes it highly sensitive to the photo-Dember effect. Its short optical absorption length and high kinetic energy of electrons after photoexcitation also enhance the photo-Dember effect. In addition, compared with GaAs, the surface electric field of InAs is weaker, so its terahertz (THz) emission mainly comes from the photo-Dember effect rather than the surface field effect. Studying its photo-Dember effect can provide important theoretical basis and technical support for the development of terahertz technology, semiconductor material research, and the development of new devices. PAM-XIAMEN can provide InAs substrates for related basic academic research, with the following parameters for reference only:
1. InAs Substrate for Photo-Dember Effect Research
| Item | InAs Wafer |
| Diameter | 2~4inch |
| Conduction Type | P（Zn-doped） |
| Orientation | (111), (110) or (100)+/-1 deg |
| Thickness | 500+/-25um, 600+/-25um, 900+/-25um |
| Carrier Concentration | （1-5）E18cm-3 |
| Mobility | 60～300cm2V-1S-1 |
| EDP | <1000cm-2 |
| Orientation Flat | SEMI Standard |
| Surface Finished | SSP |
2. What Is Photo-Dember Effect?
The photo-Dember effect is a mechanism for generating pulsed terahertz radiation under femtosecond pulse light excitation, which depends on the difference in diffusion rates between electrons and holes in semiconductors. When ultrafast laser pulses irradiate the surface of a semiconductor, they excite the generation of free electron and hole pairs. Due to the significantly faster diffusion rate of electrons compared to holes, the two will diffuse in opposite directions, forming charge separation and generating an electric dipole moment near the semiconductor surface, known as the photo-Dember dipole moment. This dipole moment directly radiates terahertz electromagnetic waves perpendicular to the direction of the semiconductor surface.
The strength of its effect is influenced by three factors: the difference in carrier mobility of semiconductor materials determines radiation efficiency; The energy, pulse width, and intensity of laser pulses affect the carrier concentration and relaxation process; An external magnetic field can regulate the direction of terahertz radiation by changing the orientation of the dipole moment. This effect is currently mainly applied in terahertz time-domain spectroscopy to generate terahertz radiation pulses, supporting research and applications in terahertz spectroscopy, imaging technology, and industrial non-destructive testing. This effect exists in most semiconductors, but is particularly strong in narrow bandgap semiconductors such as InAs and InSb due to their high electron mobility.
3. Research on Terahertz Emission Generated by Photo-Dember Effect of InAs
Scholars have studied the terahertz radiation characteristics generated by photo-Dember effect of InAs materials under femtosecond laser pulse excitation. By developing a fluid dynamics model, the physical mechanism of this effect has been simplified and analyzed, and compared and verified with ensemble Monte Carlo (EMC) simulation results.
Research has shown that the amplitude of transient photocurrent is directly proportional to the square difference between the excited electron and hole velocities. The intensity of terahertz radiation is proportional to the light intensity at low pulse intensities, ranging from 3/2 to 2 times the power, while it shows a saturation trend at high intensities and has a significant dependence on the duration of the light pulse.
The experiment also found that the radiation intensity of p-type InAs is significantly higher than that of n-type InAs, and the electron valley transfer process reduces the radiation energy. However, when the valley coupling is strong enough, characteristic peaks appear in the energy spectrum. The research results indicate that the material type (p-type/n-type), light pulse parameters (intensity, duration), and inter valley electron transfer behavior all affect the terahertz radiation characteristics of InAs.
Whether you need InAs wafer for research or for industrial applications, please contact us email at [email protected] and [email protected].