随着高速半导体器件的发展,高电子迁移率晶体管(HEMT)的工作频率已经达到亚太赫兹波段,所以无法简单地通过传统电学方法进行检测。鉴于此,必须采用超快光学方法测定HEMT器件的截止工作频率。利用持续时间更短的飞秒脉冲激光瞬时关断处于饱和工作状态下的HEMT器件,并且采用太赫兹时域光谱技术测量在器件被关断后电流的变化情况(时间是皮秒量级),最后,利用所测量到的太赫兹波形(即源漏电流随时间变化的曲线)和截止工作频率的关系,直接推算出可达到亚太赫兹波段的HEMT器件的截止工作频率。 With the development of high-speed semiconductor devices, the operating frequency of high electron mobility transistor (HEMT) has reached the Asia-Pacific Hertz band, so it can not be easily detected by traditional electrical methods. In view of this, the cut-off frequency of the HEMT device must be determined using an ultra-fast optical method. The use of shorter duration femtosecond pulsed laser instantaneously turns off the HEMT device under saturation operation and uses terahertz time-domain spectroscopy to measure the current variation (time in picoseconds) after the device is turned off, Finally, the cut-off frequency of the HEMT devices that reach the Asia-Pacific Hertz band can be directly estimated by using the measured terahertz waveform (that is, the curve of the source-drain current with time) and the cutoff operating frequency.