Effect of gamma irradiation with low doses on npn bipolar junction transistors

Other Title(s)

نظرية تأثير أشعة غاما المنخفضة على الترنسيستورات ثنائية القطبية من النوع npn

Dissertant

Muhammad, Muawiyah Ibrahim Hamad al-Nil

Thesis advisor

Jawad, Hasan Muhammad

University

Omdurman Islamic University

Faculty

Faculty of Sciences and Technology

Department

Department of Physics

University Country

Sudan

Degree

Ph.D.

Degree Date

2009

English Abstract

Abstract of thesis presented to the Senate of Omdurman Islamic University in fulfillment of the requirement the degree of Doctor Philosophy.

Effect of gamma irradiation with low doses on npn bipolar junction transistors By : Moawia Ibrahim Hammed Elnil Mohammed January 2009 Supervisor : Prof.Hasan Mohammed Jawad In recent years, intensive investigations of the radiation hardness on bipolar junction transistors (BJTs) and metal oxide semiconductor field effect transistors (MOS) devices integrated in computers and (MOS) technology were studied in order to analyze the performance changes of the individual devices with irradiation and to find the bast dosing strategies .

In the present work the measurements of the gamma irradiation effects with energy of 1.25MeV emitted from 60Co source with activity of 37GBq and doses ranging between 100-1000mGy on commercially available npn bipolar junction transistors of numbers between (Sc3330 t0 Sc3340 ) are presented.

The measurements were done at the radiation isotope center, Khartoum.

The collector current (Ic) values, collector – emitter voltage (Vce) at constant values of the base current (Ib) of common emitter npn transistor (output characteristics) before and after gamma irradiation doses were studied.

Also, in this work the following parameters of npn bipolar junction transistor were measured and analyzed : The forward current gain (Ai) values, the corresponding value of (∝), the current gain factor (1/ Ai), the Tran conductance (gm), the out put impedance (Z), the voltage gain (Av) and the power gain (Ap) values before and after gamma irradiation.

It was observed that there is a decrease on collector current (Ic) values after gamma irradiation as compared to its values before gamma irradiation and this reduction in (Ic) values is mainly caused by production, recombination and subsequent trapping of holes introduced by gamma irradiation.

Observations and measurements show that the strong and slight gamma irradiation effects on (Ic) and (Ib) values lead to a decrease in the current gain (Ai) and voltage gain Av values as compared to this values before gamma irradiation.

Using the large sets of data the variation of the transconsconductance (gm) and the output impedance (Z) values with gamma doses are studied and it was found that (gm) values increased parabollically white (Z) decreased exponentially with gamma doses.

From the graphs of the voltage gain (Av) and the power gain (Ap) values versus gamma doses it was observed that the (Av) values decreased nearly uniformly with gamma doses.

Also the (Ap) values decreased sharply, reached minimum at 100mGy and then decreased slowly with gamma doses greater than 100mGy.

The results presented in this work shows that the current gain (Ai) and the collector current (Ic) values first deceased after gamma irradiation of doses smaller or equal to 100mGy and then started to increase at gamma doses above 100mGy.

Also the comparison between the present and the previous studies indicated that the (Ai) and (Ic) values increased on increasing gamma doses to values above 100mGy in agreement with a previous study at doses ranging between 0.1-0.5MGy [1].

The present results and studies show that the common emitter npn transistor collector current (Ic) is very sensitive to gamma irradiation.

This property makes the npn bipolar transistor to be used as dosimeter for determination of the approximate values of the gamma dose and the activity of the gamma ray source.

Main Subjects

Physics

Topics

• Gamma ray
• Semiconductors

No. of Pages

131

Table of Contents

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-376910