Research And Application Of GaN Transceiver Integrated Optoelectronic Chip

After entering the 21 st century,GaN,as one of the representatives of the third-generation semiconductor materials,has gradually become a hot spot of scientific research.The optoelectronic devices based on it have unique advantages in terms of forbidden band width,electron saturation drift efficiency,anti-interference and other aspects.These devices have been widely used and developed in military,civilian,medical and other detection and sensing fields.With the improvement of people’s living standards and the enhancement of health and safety awareness,heart health issues have received more attention.However,heart rate and pulse detectors on the market usually adopt a separate layout of transceiver components,which will affect the structure,cost and sensitivity of the system.Therefore,GaN optoelectronic devices in the form of optoelectronic integration will gain new opportunities and developments in the field of medical health monitoring.Based on the above circumstances,a GaN integrated optoelectronic chip with a size of 1.5mm ×2.5mm was designed and prepared in this study.The chip integrated two Light Emitting Diodes(LED)together through a homo-integration method,and took advantage of the physical phenomenon of the overlapping region(474nm-535nm)between the electroluminescence spectrum and the photoresponse spectrum,to use the chip as both an optical transmitter and a Photodetector(PD).Then,using the chip as the core,communication and single-chip sensing tests were carried out.In the communication test,the chip,acting as a PD,was able to effectively receive a pseudo random binary sequence(PRBS)signal with a speed of 100 bps sent from the other end;in the single-chip sensing test,the chip,acting as both an optical transmitter and a PD,was able to achieve a sensing distance of up to 8mm,and could effectively restore the frequency variation of the finger’s movement in the pulse signal simulation test.The above test results indicate that the device can not only receive optical signals from the same device structure,but also has sufficient sensing bandwidth and potential for detecting heart rate and pulse signals.Based on the experimental results,the overall design of a GaN integrated heart rate and pulse sensor was completed.The sensor uses an emitter to shine light onto the surface of the finger.Due to the variation in the finger’s light absorption caused by factors such as heartbeats,the reflected light signal modulated by the finger carries human pulse information and is detected by the PD.In terms of hardware,the amplification and shaping of the optoelectronic signal were completed to expand the amplitude range of the signal to 40 m V for subsequent signal processing.The hardware design of the development board was also completed.In terms of software,the calculation and display transmission of heart rate information were completed.Subsequently,after packaging,the system can not only effectively detect heart rate and pulse signals but also meet the requirements of integration and low-cost design,making it convenient for residents to use in daily life.To evaluate the performance of the sensor,a simultaneous detection comparison experiment with a commercial pulse detection sensor was conducted on the same sample.The results showed that the maximum absolute error value between the two was 2,and the maximum relative error rate(RER)was 2.50%.