超结硅锗碳异质结双极晶体管机理研究与特性分析优化

提出一种超结硅锗碳异质结双极晶体管(SiGeC HBT)新结构.详细分析了新结构中SiGeC基区和超结结构的引入对器件性能的影响,并对其电流输运机制进行研究.基于SiGeC/Si异质结技术,新结构器件的高频特性优良;同时超结结构的存在,在集电区内部水平方向和垂直方向都建立了电场,二维方向上的电场分布相互作用大大提高了新结构器件的耐压能力.结果表明:超结SiGeC HBT与普通结构SiGeC HBT相比,击穿电压提高了48.8%;更重要的是SiGeC HBT器件中超结结构的引入,不会改变器件高电流增益、高频率特性的优点;新结构器件与相同结构参数的Si双极晶体管相比,电流增益提高了10.7倍,截止频率和最高震荡频率也得到了大幅度改善,很好地实现了高电流增益、高频率特性和高击穿电压三者之间的折中.对超结区域的柱区层数和宽度进行优化设计,随着柱区层数的增多,击穿电压显著增大,电流增益有所提高,截止频率和最高震荡频率减低,但幅度很小.综合考虑认为超结区域采用pnpn四层结构是合理的.

Mechanism and characteristic analysis and optimization of SiGeC heterojunction bipolar transistor with super junction

A novel SiGeC heterojunction bipolar transistor (HTB) with super junction is presented. The effects of SiGeC base and super junction on device performance are analyzed in detail, and current transport mechanism of novel device is studied. Based on SiGeC/Si heterojunction technology, the high frequency characteristic of the novel device can be excellent. The breakdown voltage of device is improved greatly, because of two-dimensional direction of the electric field distribution in the collector region. The results show that the breakdown voltage of SiGeC HBT with super junction is increased by 48.8%, compared with that without super junction. More importantly, the introduction of super junction changes neither the high current gain nor the high frequency characteristics of SiGeC HBT. Compared with the Si bipolar transistor (BJT) with the same parameters, the novel device has a current gain that increases 10.7 times, and its cutoff frequency and maximum oscillation frequency are also improved greatly. A good trade-off is achieved among high current gain, high frequency and high breakdown voltage, in the novel SiGeC HBT with super junction. The layers and width of column region are designed to be optimal. With the increase in the number of column region layers, the breakdown voltage of the novel device is increased significantly, the current gain is improved somewhat, and the cutoff frequency and maximum oscillation frequency are reduced slightly. Taken together, the pnpn four-layer structure of super junction region is reasonable.