Researcher Kang Tingting, State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, etc., with the support of the 100-member program of the Chinese Academy of Sciences, has made new progress in the study of nitride photoconductivity under extremely weak light. The researchers used the optoelectronic experimental physics under extreme conditions (ie weak light, very low temperature, strong magnetic field) as the main research direction, and designed a low-light photoconductive measurement system using LED (light-emitting diode) as the light source [shown below], measuring Photoconductive behavior of InN. Taking the power density of light as an indicator, the incident light intensity ranges from 10-9 to 10-6 W/cm2 (only equivalent to the moonlight intensity (~10-7 W/cm2) on the ground at full moon). Internationally, photoconductivity research uses glare (0.1 - 100W/cm2), which is 100,000 to 1 billion times the experimental light intensity. The researchers found that InN "negative continuous photoconductivity" completely disappeared in low light, and its behavior under strong light also accorded with three characteristics of light heating effect: (1) conforming to the trend of thermal effect; (2) long relaxation Yu time; (3) enhanced with temperature drop. The results show that InN "negative continuous photoconductivity" is derived from the light heating effect, indicating that InN has a strong electron-lattice effect; InN:Mg has n-to-P-type transition and is no longer supported by photoconductivity results. . The experimental results prove that the research method that does not consider the light heating effect in the photoconductive research is completely incorrect. The results obtained are published in Applied Physics Letters, an important publication in the field of nitrides [Appl. Phys. Lett. 110, 042104 (2017)]. (a) Establish a low-light (low-temperature LED) weak thermal radiation photoconductive measurement system. The low temperature metal cover (~40K) is used to shield the 300K black body heat radiation emitted by the room temperature component. (b) Physical image of the light heating effect Photoconductivity measurement is an important method to study the photoelectric properties of materials. It studies the electrical properties of objects under electromagnetic wave illumination. Since W. Smith conducted research on the photoconductive behavior of selenium in 1873, photoconductivity has been an important research direction in optoelectronics, condensed matter physics and other disciplines, and directly led to the establishment and development of photodetectors. . However, due to the adoption of strong light (mainly laser), the field has been controversial. On the other hand, as a third-generation semiconductor, nitride has a wide range of applications in the fields of consumer electronics and white light illumination. Akasaka, Amano and Nakamura received the 2014 Nobel Prize in Physics for their contributions in the field of nitrides. Indium nitride (InN), as the only material in the Group III nitride with a band gap of infrared (~0.7eV), has important application prospects in applications such as nitride-based infrared detectors and full-spectrum high-performance solar cells. Recently, in the field of InN, several research groups have reported in the famous academic journals such as Phys. Rev. B, Appl. Phys. Lett., Sci. Rep. that there is a so-called "negative persistent photoconductivity" in InN. Photoconductivity, NPPC), that is, after the intense light (laser) irradiation of InN, the conductance will slowly decrease (the so-called "negative" photoconductivity). This is a spy hidden camera with different lens angles, complete functions and a wide range of applications. Spy Hidden Camera,hidden video camera,spy camera,hidden spy camera,hidden cameras Jingjiang Gisen Technology Co.,Ltd , https://www.jsgisengroup.com
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