工作在液氮温度下的低频低噪声双极晶体管的研究

对双极晶体管的低温物理模型和低频噪声模型进行了研究，认为低温下硅双极晶体管电流增益下降的主要原因是低温下非理想基极电流的增加。同时指出，低温下硅双极晶体管１／ｆ噪声的增大，是由于低温下电流增益的减小和载流子在体内和表面的复合增加。通过优化设计，做出了一种低温、低频、低噪声硅双极晶体管。测试表明，在室温（３００Ｋ）下，电流增益、低频转折频率、１ｋＨｚ点的噪声电压分别为β≥８００，ｆ＿Ｌ≤３０Ｈｚ，Ｅｎ（１ｋＨｚ）≤１．５ｎＶ／　　；低温（７７Ｋ）下，电流增益、低频转折频率、１ｋＨｚ点的噪声电压分别为β≥３０，ｆ＿Ｌ≤３００Ｈｚ，Ｅｎ（１ｋＨｚ）≤１．２ｎＶ／。

Investigation of Low Frequency Low Noise Bipolar Transistors Working at Liquid Nitrogen Temperature

In this paper, the research of low temperature physical model and low frequency noise model of silicon bipolar transistor has been conducted.We found that the current gain of silicon bipolar transistors at low temperature de-creased fast because of the increased non-ideal base current, and that the high1/f noise at low temperature was due to the low current gain and the high re-conbination in either bulk or surface area. A low temperature low frequency low noise silicon bipolar transistor was manufactured through optimized de-sign. The measurement results showed that it had parameters of β≥800,f_L≤30Hz, En(1kHz)≤1. 5nV/at room temperature(300K), and β≥25,f_L≤300Hz, En(1kHz)≤1. 2nV/at low temperature(77K).