Open AccessThe influence of uncontrolled technological impurities on the temperature dependence of the gain coefficient of a bipolar n-p-n-transistor
Author(s) -
V. B. Odzaev,
A. N. Pyatlitski,
В. А. Пилипенко,
U. S. Prosolovich,
В. А. Филипеня,
Dmitry V. Shestovski,
V. Yu. Yavid,
Yu.N. Yankovski
Publication year - 2021
Publication title -
vescì nacyânalʹnaj akadèmìì navuk belarusì. seryâ fìzìka-matèmatyčnyh navuk
Language(s) - English
Resource type - Journals
eISSN - 2524-2415
pISSN - 1561-2430
DOI - 10.29235/1561-2430-2021-57-2-232-241
Subject(s) - bipolar junction transistor , impurity , materials science , analytical chemistry (journal) , equivalent series resistance , wafer , atmospheric temperature range , diffusion , common emitter , series (stratigraphy) , doping , optoelectronics , current (fluid) , transistor , chemistry , voltage , electrical engineering , thermodynamics , paleontology , physics , organic chemistry , chromatography , biology , engineering
Herein, the temperature dependences of the static current gain (β) of bipolar n-p-n-transistors, formed by similar process flows (series A and B), in the temperature range 20–125 °С was investigated. The content of uncontrolled technological impurities in the A series devices was below the detection limit by the TXRF method (for Fe < 4.0 · 10 9 at/cm 2 ). In series B devices, the entire surface of the wafers was covered with a layer of Fe with an average concentration of 3.4 ∙ 10 11 at/cm 2 ; Cl, K, Ca, Ti, Cr, Cu, Zn spots were also observed. It was found that in B series devices at an average collector current level (1.0 ∙ 10 –6 < I c <1.0 ∙ 10 –3 A) the static current gain was greater than the corresponding value in A series devices. This was due to the higher efficiency of the emitter due to the high concentration of the main dopant. This circumstance also determined a stronger temperature dependence of β in series B devices due to a significant contribution to its value from the temperature change in the silicon band gap. At I c < 1.0 ∙ 10 –6 A β for B series devices became significantly less than the corresponding values for A series devices and practically ceases to depend on temperature. In series B devices, the recombination-generation current prevailed over the useful diffusion current of minority charge carriers in the base due to the presence of a high concentration of uncontrolled technological impurities. For A series devices at I c < 10 –6 A, the temperature dependence of β practically did not differ from the analogous dependence for the average injection level.