In this paper,the N type annealing of medium wave MCT materials is implemented by using mercury rich open tube heat treatment equipment,and the problem of how to control the mercury vapor reflux is studied and solved.Comparative experiments are carried out at the same annealing temperature and annealing time using the open tube annealing process and the closed tube annealing process,and it is found that with the increase of the annealing time,the Hall concentration of the chips treated by the two processes show a decreasing trend and the carrier mobility show an increasing trend.When the annealing temperature and annealing time are the same,the carrier mobility of the open tube annealing process is higher.The I V test and the final test of the device assembly of the chip with open tube annealing process show better performance.