Keywords: electric absorption spectrum, electric field induced absorption spectrum, charge injection absorption spectrum, EIEAS, CIEAS, charge modulated absorption spectrum, Stark effect, band gap measurement, exciton state, quantum well band transition, electric field induced effect, injected charge induced effect
▌ Product introduction
An electrical absorption spectrometer (EAS) is a technique for studying the properties of semiconductors and other materials by measuring the change in the absorption of light by a sample when an electric field is applied. The sample information of the first and second order effects of the absorption coefficient and the electric field can be obtained by the electric absorption spectrum. Among them, the Stark effect (Box1) is a typical physical effect that leads to the generation of electrically absorbed signals, and can also be used to study charge-modulated absorption spectra. Excion includes two modules, electric field induced absorption spectroscopy (EIEAS) and charge injection absorption spectroscopy (CIEAS), which allow users to flexibly study electric field induced effects and injection charge induced effects.
Excion is the world's first commercial electrical absorption spectroscopy device, which was jointly developed by researchers and engineers from Oriental Spectra Technology in collaboration with expert members from the University of Cambridge, City University of Hong Kong, Sun Yat-sen University and South China University of Technology.
From the application direction, EAS has a wide range of applications, especially in the field of semiconductor physics and optoelectronics. Here are some key areas and directions for EAS applications:
(1) Band gap measurement: EAS can be used to measure the band gap of semiconductors. Under the application of an applied electric field, the absorption starting point near the band edge shifts, allowing the band gap energy to be precisely determined.
(2) exciton states: In semiconductors, excitons - bound states of electrons and holes - can be studied using EAS. An applied electric field can change the energy required for these excitons to exist, which manifests itself as a change in the absorption spectrum.
(3) intersubband transition: For quantum-confined structures like quantum Wells, lines, and points, EAS can be used to observe transitions between subbands, which is important for understanding the effect of a material's size on electronic properties.
(4) Material quality assessment: EAS can help detect impurities and defects in semiconductor samples. Changes in the absorption spectrum may indicate the presence of defects or impurities that affect the electronic structure.
(5) Characterization of optoelectronic devices: When developing devices such as leds, photodetectors, and solar cells, EAS can provide an understanding of the behavior of materials in their operating state. This includes studying the effect of electric fields on the efficiency of light emission or absorption processes.
(6) Modulators and switches: Semiconducter-based optical modulators and switches rely on the Stark effect, which can be characterized and optimized by EA spectroscopy.
(7) Nonlinear optical properties: Materials with nonlinear optical properties can be studied using EAS to understand how they interact with strong electric fields, which is critical for optical signal processing and communication applications.
(8) Quantum information processing: In the emerging field of quantum computing, EAS can assist in the design and analysis of semiconductor structures that may serve as qubits or other quantum optical components. In summary, the application of EA spectroscopy enables researchers and engineers to gain insight into the electronic properties of materials, help advance materials science, and optimize optoelectronic devices for various industries including semiconductors, telecommunications, energy, lighting and display, and quantum computing.
The general use process of the Excion electric absorption spectrometer is as follows:
(1) Sample preparation: A thin film sample of a semiconductor or other material is prepared and an electrical contact point is attached so that an electric field is applied to it. A common way is to prepare the sample into a sandwich structure.
(2) Apply electric field: Apply DC or low-frequency electric field to the sample, and the size, frequency and bias value of the electric field can be flexibly set in the software.
(3) Light absorption measurement: In the mode of EIEAS or CIEAS, the scanning wavelength, scanning electric field frequency, scanning electric field size and other test variables are set to perform variable dependent light absorption measurement.
(4) Data analysis: By comparing the absorption spectra when there is no electric field, the absorption changes corresponding to the transformation between different electronic states in the material can be observed. Applying an electric field may cause a shift in the absorption peak, indicating a change in the energy required for the electron to transition between energy levels. Excion provides rich data analysis functions such as data smoothing, peak splitting, first order guide, second order guide, exponential fitting, polynomial fitting, etc.
(5) Data export: Excion provides convenient data export function, which can export data in TXT/CSV and other text formats.
(6) Data interpretation: The data obtained by users from Excion can be used to study various properties of semiconductor materials, including the band gap (the energy difference between the valence band and the conduction band), the density of states near the edge of the band, the built-in electric field, and the presence of defects or impurities that may affect the electronic structure.
With its high sensitivity and accuracy, versatility, ease of use, high throughput detection, durability, complete technical support and after-sales service, Excion is the ideal choice for industry and research.
▌ Product characteristics
■ Multi-functionality: Excion draws on the most cutting-edge electrical absorption research and industrial application research results, integrates two principle modes of EIEAS and CIEAS, integrates two optical path detection modes of transmission and reflection, and can also carry out more than 8 kinds of physical variable scanning and single point detection tests;
High sensitivity and accuracy: Excion uses the latest modulation, sensing and detection technology to capture extremely small changes, and its measurement results have a high degree of reliability and repeatability to ensure the accuracy of the data;
Wide spectral range: This spectrometer covers a wide range of bands from ultraviolet to near-infrared (200-2500nm), suitable for a variety of different electrical absorption spectral analysis needs;
High throughput detection: Artificial intelligence design concept, a high degree of automation design, high-speed data acquisition system enables Excion to quickly complete spectral scanning, greatly improving work efficiency and experimental throughput;
Easy to operate: Excion's user interface design is intuitive and easy to understand, even non-professionals can easily get started, with typical 'Plug & Play' and 'Turn-key' characteristics. ;
□ Stability and reliability: Excion uses high-quality parts and precision manufacturing process, introduces perfect error handling and design to ensure long-term stable operation of the instrument and reduce maintenance costs;
□ Perfect technical support and after-sales service: We provide Excion with comprehensive technical support and warranty services to ensure that users have no worries during use.
▌ Measurement mode
Measurement mode
□ Single point measurement;
□ Scanning measurement;
Wavelength scanning
Frequency sweep
Phase sweep
Light source intensity scanning
Field intensity scanning
Injection current scanning
Temperature scan: variable temperature test
Principle model
Electric field induced absorption Spectroscopy (EIEAS)
Charge injection absorption Spectroscopy (CIEAS)
Charge modulation absorption spectrum, etc
Electric absorption spectrum
▌ Functional parameter
Excion electrical absorption spectrometer |
Feature | Principle function | EIEAS |
CIEAS |
Optical circuit function module | Transmission type |
Reflecting type |
Pump optical module | Yes/no (405/450/520/980nm optional) |
Detection wavelength function module | 200-300 nm |
300-1100 nm |
1100-1800 nm |
1800-2500 nm |
Variable temperature function module | Normal temperature |
poikilothermy | 4 K-300 K |
78 K-300 K |
Room temperature -500 K |
Visualization module | Yes/no |
Electrical signal | Module 1 | frequency | 10 mHz~105 KHz |
voltage | AC,0-20V; DC,0-10V. |
Electric field | Sample preparation decision |
Electric current | Sample preparation decision |
Module 2 | frequency | 45 Hz-999.9Hz |
voltage | AC,0-350V; DC,0-±500V |
Electric field | Sample preparation decision |
Electric current | Sample preparation decision |
Wavelength range | 200-2500nm(optional) |
Minimum step wavelength | ± 0.1nm (typical value) |
Wavelength regulation mode | Auto |
Detection depth | Rank 6 |
Detection sensitivity | 10−4 OD |
software |
Feature | 1. The Excion software package |
2. Test and analysis function
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▌ Product application
□ Band gap measurement;
□ exciton state study;
□ Quantum well band transition;
□ Material quality assessment;
□ Characterization of optoelectronic devices;
□ Modulator and switch;
□ Nonlinear optical characteristics;
□ Quantum information processing.
