In the field of photoelectric detection technology, the spectral response characteristics of the detector
are the core indicators for measuring its performance. Whether it is semiconductor photovoltaic devices,
infrared sensors or quantum dot detectors, the precise measurement of parameters such as spectral responsivity
and quantum efficiency directly determines the practical application effects of the devices in fields such
as optical communication, environmental monitoring and biomedicine. With 20 years of technological
accumulation, Beijing Saifan Optoelectronic Instrument Co., Ltd. has launched the 7-DRSpec detector
spectral response testing system. With an ultra-wide spectral range of 200-2500nm, a wavelength accuracy
of ±0.2nm, and a modular intelligent design, it redefines the industry standard for the performance evaluation
of photodetectors.
I. Technological Breakthrough: Full coverage from deep ultraviolet to mid - and far-infrared
The 7-DRSpec system breaks through the wavelength limitations of traditional spectrometers, supporting
full-spectrum testing from 200nm to 2500nm, covering four major bands: deep ultraviolet (such as solar
blind spot detectors), visible light (such as solar cells), near-infrared (such as fiber optic sensors), and mid-far-infrared
(such as thermal imagers). The system adopts a combined design of a three-grating monochromator and
a six-stage filter wheel. Through meticulous research and development of worm gear and worm transmission
and stepper motor subdivision technology, it achieves a minimum motor step distance of 0.005nm, effectively
eliminating multi-level spectral interference and ensuring spectral purity. For instance, in the testing of
InGaAs infrared detectors, the system can accurately capture the response peak in the 1550nm communication
band, with a wavelength repeatability of ±0.1nm, meeting the strict requirements of high-end optical communication
devices.
Its composite light source is composed of a deuterium lamp (200-400nm) and a halogen tungsten lamp
(400-2500nm). The output current drift of the power supply is only 0.04%/h, ensuring the stability of
long-term testing. To address the measurement errors caused by multi-level spectra of light sources
such as xenon lamps, the system works in coordination with the monochromator through the filter wheel,
compressing the spectral bandwidth to an adjustable range of 0.2-10nm, significantly enhancing the signal-to-noise
ratio. For example, in the test of GaAs detectors, the system reduces the background noise to below 2mV
through narrowband filtering, making the detection of weak signals possible.
Ii. Scenario-based Innovation: Full-process support from micro-nano devices to large-area detection
For different detector structures, 7-DRSpec provides dual test modes:
Illuminance method (integrating sphere mode) : It is applicable to micro-nano devices with an effective
area of less than 1mm² (such as quantum dot detectors). By using an integrating sphere, the uniformity
of the light spot is less than 1%. Combined with a CCD microscope and a precision displacement stage,
precise positioning of a 40μ m-level light spot can be achieved. For instance, in the testing of perovskite
nanowire detectors, the system eliminates spot non-uniformity through an integrating sphere, reducing
the irradiance responsivity measurement error to less than 2%.
Flux method (reflection imaging mode) : For large-area detectors with an effective area greater than 1cm²
(such as photovoltaic cells), a total reflection imaging optical path is adopted, which increases the light
utilization rate by 30% and achieves a signal-to-noise ratio of over 1000:1. For instance, in the test of
TOPCon solar cells, the system eliminates the chromatic aberration problem of the transmissive system
through a reflective optical path, making the deviation of the quantum efficiency calculation result from
the theoretical value less than 1.5%.
Iii. Intelligent Interaction: A closed-loop Experience from data collection to Report Generation
The system is equipped with the TurnKey "one-click test" software, which supports fully automatic spectral
scanning and parameter calculation. Users can set test parameters (such as wavelength range, scanning
step size, and bias voltage) through the 10.1-inch touch screen, and the software will complete it automatically:
Spectral responsivity (RΦ) calculation: Based on the principle of substitution method, by the current ratio
of the standard detector to the detector under test, combined with the system calibration data, the absolute
spectral radiation flux responsivity (A/W) is directly output.
Quantum efficiency (η) derivation: The built-in formula η=1.24×RΦ(λ)/λ(μm) is used to calculate the variation
curve of quantum efficiency with wavelength in real time.
Dynamic parameter analysis: Supports synchronous testing of parameters such as response time, dark
current, and normalized detection rate, and generates detailed reports including spectra, data tables,
and error analysis. For example, in the test of InSb infrared detectors, the system can synchronously
output the responsivity curve and the dark current curve, providing multi-dimensional data support for
device optimization.
Iv. Modular Architecture: Elastic scalability from basic testing to research-level applications
7-DRSpec adopts an open modular design, allowing users to flexibly select and configure functional
modules according to their needs:
Variable temperature test module: Supports liquid nitrogen cooling (-196℃) to high-temperature baking
(300℃), suitable for studying the influence of temperature on the performance of detectors. For instance,
in the test of the HgCdTe detector, the system reveals the inflection point of its responsiveness varying
with temperature through the variable temperature module, providing a basis for the optimization of the
device packaging process.
Bias scanning module: Supports dynamic scanning with voltages ranging from 200μV to 505V and currents
from 20fA to 200mA, and is suitable for studying the influence of applied bias on detector sensitivity. For
example, in the test of APD avalanche photodiodes, the system determines its optimal gain range through
bias scanning, increasing the detection sensitivity by 20%.
Multi-light source expansion module: Compatible with various light sources such as lasers, leds, and xenon
lamps, and supports user-defined spectral distribution. For instance, in the photovoltaic cell test simulating
the solar spectrum, the system achieves a spectral matching degree of over 95% through a dual-light source
system (AM1.5G filter + halogen tungsten lamp), making the external quantum efficiency (EQE) test results
closer to the actual working conditions.
V. Industry Practice: Value Realization from the Laboratory to the Production Line
In the photovoltaic field, 7-DRSpec has been applied to the quality inspection of the back passivation
layer of PERC cells. By analyzing the carrier recombination mechanism through spectral response curves,
it has helped increase the cell efficiency to over 24.5%. In the semiconductor industry, the system provides
a quantitative standard for dark current suppression of INP-based detectors, reducing the device noise
equivalent power (NEP) to below 10⁻¹⁴W/Hz¹/². In the biomedical field, the system optimizes the fluorescence
labeling efficiency of upconversion nanoparticles through near-infrared spectral response testing, providing
a detection solution with a higher signal-to-noise ratio for in vivo imaging.
Conclusion: Drive the future of photoelectric detection with innovation
The 7-DRSpec detector spectral response test system of SOFN Instruments is not only a precision
instrument but also a "digital twin platform" for the research and development and production of photodetectors.
Its full-band coverage, high-sensitivity detection and modular expansion capabilities provide reliable technical
support for innovative breakthroughs in fields such as optoelectronic devices, new energy and environmental
monitoring. Choosing 7-DRSpec means choosing the precise analysis capability that keeps pace with
the cutting-edge of global optoelectronic technology.
Consult immediately
Beijing SOFN Instruments Co., LTD
National Service Hotline: 010-80885970
Official website: http://www.7-s.com.cn
Wechat official Account: Saifan Optoelectronic Instruments
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