A paper published online today by Nature Nanotech said scientists used the femtosecond technology for the first time to capture the electronic state changes in semiconductor materials. The result will provide unprecedented insight into the semiconductor core devices. Technological advances in semiconductor devices have been concentrated and evident since the late 20th century, such as transistors, diodes and solar cells. At the heart of these devices is precisely the internal motion of electrons in semiconductor materials. However, measuring the motion of the electrons is a major challenge due to the fast speed of the electrons. Until 2008, Swedish scientists used femtosecond pulses with ultra-short and super-powerful characteristics to capture a single electronically moving continuous film for the first time with a strong laser-generated transient pulse. Unfortunately, in the current research on semiconductor electronic dynamics, the dual limitation of the spatial resolution of the optical probe or the temporal resolution of the electron probe still remains and scientists have not found any direct observation before. In the new study, scientists at Okinawa University of Science and Technology of Japan (OIST) have developed a new method to visualize changes in electronic states in semiconductor materials. They use a strong laser pulse to irradiate the material, causing a change in the state of the material. After a period of time, a weak laser pulse is emitted. At this point, some of the electrons on the surface of the material are excited and the researchers collect the electrons and image them electronically. Relying on the continuous irradiation of a weak laser, the electrons accumulate and eventually form a picture of the electron distribution inside the material. The researchers then changed the time lag between intense and weak lasers to get new electron distribution pictures again. After sequentially increasing the time difference, a series of photos can be obtained, and the relationship between the position of the electron and the excitation time can be established. Eventually, the electron is formed from the excited state to the ground state (from the high energy state to the low energy state) after being excited by the light video. Previously, scientists speculated that the movement of electrons was based on the photoelectric interaction of materials. The new study was the first time that human beings captured the movement of electrons inside the semiconductor material using the femtosecond technology. It was the first time that the electronic state of the material was directly observed. Comments Scientists have always dreamed of observing rather than speculating on electronic motion. To do this requires the instrument to have a very high "quality" in terms of spatial resolution and temporal resolution, which can not be met by conventional equipment. With the help of femtosecond imaging, scientists have realized direct observation for the first time. It also means that mankind has started to learn more about the working mechanism of semiconductor devices to develop truly revolutionary electronic products.
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