The 4th Int'l Conference on Semiconductor Physics and Devices (ICSPD 2019) will be held from August 20-22, 2019 in Xi'an, China. This Conference will cover issues on Semiconductor Physics and Devices. It dedicates to creating a stage for exchanging the latest research results and sharing the advanced research methods. ICSPD 2019 will be an important and reliable platform for inspiring international and interdisciplinary exchange at the forefront of Semiconductor Physics and Devices. The Conference will bring together academicians, engineers, educators and policy-makers from all over the world, and we hope that you will take this opportunity to join us for academic exchange and visit the city of Xi'an.