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CN-122016735-A - Photocurrent imaging system based on probe station and electrometer

CN122016735ACN 122016735 ACN122016735 ACN 122016735ACN-122016735-A

Abstract

The invention relates to the technical field of photoelectric detection, in particular to a photocurrent imaging system based on a probe station and an electrometer. The system generates a focused detection beam through an optical path system, irradiates a sample borne by a probe platform after being spatially modulated by a mask plate, acquires a weak photocurrent signal generated by the sample by utilizing an electrometer, and generates a high-resolution photocurrent distribution image by combining the scanning motion of a high-precision electronic control displacement platform with intelligent processing of computer software. The invention innovatively designs a physical driving signal enhancement model, a multidimensional noise suppression algorithm and a dynamic imaging optimization formula, solves the problems of low weak photocurrent detection precision, large scale engagement error and insufficient imaging efficiency in the prior art, realizes the accurate quantitative analysis of the photoelectric characteristics of materials, is suitable for the scenes of semiconductor device research and development, solar cell performance evaluation, biosensor detection and the like, and has both detection precision and application flexibility.

Inventors

  • LAN YONG

Assignees

  • 广东艾维特科技有限公司

Dates

Publication Date
20260512
Application Date
20260123

Claims (7)

  1. 1. A photocurrent imaging system based on a probe station and an electrometer is characterized by comprising an optical path system, a mask plate, a high-precision electric control displacement platform, the probe station, the electrometer, a source meter and computer software, wherein the optical path system is used for outputting a focused laser beam, the mask plate is fixed on the high-precision electric control displacement platform, the high-precision electric control displacement platform drives the mask plate to carry out two-dimensional controllable displacement so as to realize space modulation of the laser beam, the probe station is used for stably bearing a sample to be detected, the laser is focused on the surface of the sample through a microscope after being modulated by the mask plate, the sample generates photocurrent under illumination, the electrometer is electrically connected with the probe station and is used for collecting photocurrent signals generated by the sample, the source meter provides adjustable bias voltage for the sample, and the computer software is respectively in communication connection with the high-precision electric control displacement platform, the electrometer and the source meter and the computer software is used for controlling the cooperative work of all parts and receiving the photocurrent signals and generating photocurrent distribution images based on a preset algorithm.
  2. 2. The photocurrent imaging system based on the probe station and the electrometer according to claim 1, wherein the optical path system comprises a laser, an optical fiber, a space coupler, an optical filter and a light collecting sheet, laser output laser is transmitted through the optical fiber or the space coupler, and the laser output laser is sequentially filtered by the optical filter, collected by the light collecting sheet and then is incident to the mask plate.
  3. 3. The probe station and electrometer based photocurrent imaging system of claim 1, wherein the computer software executes preset algorithms including a photocurrent response coefficient calculation model, a multi-scale noise suppression algorithm, and a dynamic imaging reconstruction algorithm.
  4. 4. A photocurrent imaging system based on a probe station and electrometer according to claim 3, wherein the photocurrent response coefficient calculation model: Wherein, the method comprises the steps of, As a response coefficient to the photocurrent, In order to filter the peak value of the photocurrent signal, For the detection efficiency of the electrometer, In order to bias the voltage enhancement factor, For the output power of the laser, For the light path transmission efficiency, Is the spot area of the laser on the sample surface.
  5. 5. The probe station and electrometer based photocurrent imaging system of claim 1, wherein the multi-scale noise suppression algorithm combines kalman filtering with wavelet threshold denoising: ; ; Wherein, the For the nth data point after filtering, In order for the kalman gain to be achieved, As the raw data point of the data, In order to predict the data point, As a result of the wavelet threshold value, Is the standard deviation of the noise, which is the standard deviation of the noise, Is the data length.
  6. 6. A photocurrent imaging system based on a probe station and electrometer according to claim 3, wherein the dynamic imaging reconstruction algorithm generates an image by nonlinear mapping of photocurrent response coefficients to RGB color space, the mapping formula being: ; ; ; Wherein, the As a response coefficient to the photocurrent, 、 And The values of the three channels of RGB are respectively, 、 The minimum value and the maximum value of the photocurrent response coefficients respectively, 、 And Are nonlinear adjustment coefficients.
  7. 7. The probe station and electrometer based photocurrent imaging system of claim 1, wherein the computer software further provides photocurrent uniformity assessment and defect localization functions: The uniformity evaluation formula is: ; Wherein, the In order for the uniformity to vary by a factor, The uniformity variation coefficient is used for evaluating the quality of a sample to be detected; defect localization is achieved by calculating local response coefficient deviation, and the formula is: Wherein, the method comprises the steps of, Is the coordinates Is used for the local response coefficient deviation of (a), Is the coordinates A photocurrent response coefficient at which, Is the coordinates The average photocurrent response coefficient in the neighborhood and the local response coefficient deviation are used for positioning the defect position of the sample to be detected.

Description

Photocurrent imaging system based on probe station and electrometer Technical Field The invention relates to the technical field of photoelectric detection, in particular to a photocurrent imaging system based on a probe station and an electrometer. Background The photocurrent imaging technology is used as an advanced detection means for integrating optics and electricity, and weak current signals generated by the capturing material under illumination are converted into visual images, so that the internal photoelectric characteristic distribution of the material can be revealed, and a key technical support is provided for research and development and production in related fields. However, the existing photocurrent imaging systems suffer from the following core technical pain points: the weak photocurrent detection precision is insufficient, namely, a photocurrent signal is usually in the pA-nA magnitude, is easily influenced by environmental electromagnetic interference, system noise and light path loss, has limited input impedance and noise suppression capability, causes larger signal acquisition error and is difficult to realize accurate quantification; The multi-parameter collaborative optimization is lacking, namely the influence of factors such as light path transmission efficiency, bias voltage effect, temperature change and the like on a photoelectric signal is not quantified by a system, and the data processing lacks a collaborative model of physical driving, so that the relativity of the photoelectric signal and the actual photoelectric characteristic of the material is insufficient; The system has single function, most systems can only provide qualitative imaging results, lack quantitative analysis functions such as photoelectric characteristic uniformity evaluation, defect positioning and the like, and cannot meet the test requirements in complex scenes. In order to solve the above technical problems, a photocurrent imaging system based on a probe station and an electrometer is needed. Disclosure of Invention The invention aims to provide a photocurrent imaging system based on a probe station and an electrometer, which realizes the cooperative improvement of detection precision, imaging resolution and test efficiency by optimizing the structural design of the system, introducing a quantitative calculation model of physical drive and a multidimensional noise suppression algorithm. The aim of the invention can be achieved by the following technical scheme: A photocurrent imaging system based on a probe station and an electrometer is characterized by comprising an optical path system, a mask plate, a high-precision electric control displacement platform, the probe station, the electrometer, a source meter and computer software, wherein the optical path system is used for outputting a focused laser beam, the mask plate is fixed on the high-precision electric control displacement platform, the high-precision electric control displacement platform drives the mask plate to carry out two-dimensional controllable displacement so as to realize space modulation of the laser beam, the probe station is used for stably bearing a sample to be detected, the laser is focused on the surface of the sample through a microscope after being modulated by the mask plate, the sample generates photocurrent under illumination, the electrometer is electrically connected with the probe station and is used for collecting photocurrent signals generated by the sample, the source meter provides adjustable bias voltage for the sample, and the computer software is respectively in communication connection with the high-precision electric control displacement platform, the electrometer and the source meter and the computer software is used for controlling the cooperative work of all parts and receiving the photocurrent signals and generating photocurrent distribution images based on a preset algorithm. The laser output laser is transmitted through the optical fiber or the space coupler, and is sequentially filtered by the optical filter, converged by the light converging sheet and then incident to the mask plate. Further, the preset algorithm executed by the computer software comprises a photocurrent response coefficient calculation model, a multi-scale noise suppression algorithm and a dynamic imaging reconstruction algorithm. Further, the photocurrent response coefficient calculation model: Wherein, the method comprises the steps of, As a response coefficient to the photocurrent,In order to filter the peak value of the photocurrent signal,For the detection efficiency of the electrometer,In order to bias the voltage enhancement factor,For the output power of the laser,For the light path transmission efficiency,Is the spot area of the laser on the sample surface. Further, the multi-scale noise suppression algorithm combines kalman filtering with wavelet threshold denoising: ; ; Wherein, the For the nth data point after filtering,In