DocumentCode :
1067971
Title :
Heavy doping effects in p-n-p bipolar transistors
Author :
Tang, D.D.
Author_Institution :
IBM Thomas J. Watson Research Center, Yorktown Heights, NY
Volume :
27
Issue :
3
fYear :
1980
fDate :
3/1/1980 12:00:00 AM
Firstpage :
563
Lastpage :
570
Abstract :
This paper presents the heavy doping effects on the injection current characteristics in p-n-p transistors with a heavily doped but thin base region. The results of the present study indicate that 1) at room temperature the hole current injected into heavily doped base is insensitive to the impurity compensation effect, 2) a linear relationship between the base sheet resistance and the collector-current density is observed when the base doping density is under 1 × 1019cm-3. This relationship becomes supralinear as the doping density further increases. As a result, useful current gain exists in thin base transistors even when the base doping is greater than 1 × 1019cm-3. From the collector-current-base sheet-resistance relationship and the base doping profile, the effective intrinsic carrier density as a function of the doping density is evaluated and found to increase 8.7 times over that of pure silicon, when the average doping density is 5 × 1019cm-3(maximum doping density 1 × 1020cm-3). 3) The collector current and the current gain of the transistors become less sensitive to the temperature as the base doping density increases. We had observed a current gain up to 30 at 77 K for transistors with the maximum base doping density in the 1018cm-3range. The transistors with lower base doping suffer much more degradation in current gain when the temperature is lowered to 77 K.
Keywords :
Bipolar transistors; Charge carrier density; Doping; Electric variables measurement; Marine vehicles; Optical sensors; Photonic band gap; Semiconductor impurities; Silicon; Temperature sensors;
fLanguage :
English
Journal_Title :
Electron Devices, IEEE Transactions on
Publisher :
ieee
ISSN :
0018-9383
Type :
jour
DOI :
10.1109/T-ED.1980.19899
Filename :
1480692
Link To Document :
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