SEMICONDUCTOR(PN-JUNCTION DIODE)

A pn-junction diode (rectifier diode) is formed by sandwiching together  n-type and  p-type silicon. In practice, manufacturers grow an  n-type silicon crystal and then abruptly change it to a  p-type crystal. Then either a glass or plastic coating is placed around the joined crystals. The  n side is the cathode end, and the  p side is the anode end. The trick to making a one-way gate from these combined pieces of silicon is getting the charge carriers in both the  n-type and  p-type silicon to interact in such a way that when a voltage is applied across the device, current will flow in only one direction

SEMICONDUCTOR DIODES

Adiode is a two-lead semiconductor device that acts as a one-way gate to electric current flow.  When a diode’s  anode lead is made more  positive in voltage than its  cathode lead—a condition referred to as  forward biasing—current is permitted to flow through the device. However,  if the polarities are reversed (the anode is made more negative in voltage than the cathode)—a condition referred to as  reversed biasing—the diode acts to block current flow.Diodes are used most commonly in circuits that convert ac voltages and current into dc voltages and currents (e.g., ac/dc power supply). Diodes are also used in voltage-multiplier circuits, voltage-shifting circuits, voltage-limiting circuits, and voltage-regulator circuits.

SEMICONDUCTOR LECTURE 2 DOPING

Doping Doping refers to the process of  “spicing up”  or adding ingredients to a silicon wafer in such a way that it becomes useful to the semiconductor-device designer.

Many ingredients can be added in the doping process, such as antimony, arsenic, aluminum, and gallium. These ingredients provide specialized characteristics such as frequency response to applied voltages, strength, and thermal integrity,

SEMICONDUCTORS 1INTRODUCTION lecture 1

The most important and perhaps most exciting electrical devices used today are built from semiconductive materials. Electronic devices, such as diodes, transistors, thyristors, thermistors, photovoltaic cells, phototransistors, photoresistors, lasers, and integrated circuits, are all made from semiconductive materials, or semiconductors.1 What Is a Semiconductor? Microchips Solar cells Materials are classified by their ability to conduct electricity. Substances that easily pass an electric current, such as silver and copper, are referred to as conductors. Materials that have a difficult time passing an electric current, such as rubber, glass, and Teflon, are called insulators. There is a third category of material whose conductivity lies between those of conductors and insulators. This third category of material is referred to as a semiconductor. Asemiconductor

FG SCRAPS P.UTME, PEGS JAMB CUT OFF MARK AT 180

The Federal Government has scrapped post-Unified
Tertiary Matriculation Examinations, UTME, as a
pre-condition to gaining admission into universities
in the country.
The government and stakeholders in education
sector also pegged 180 as benchmark for 2016
admission into universities, polytechnics and
colleges of education to improve quality of
education in Nigeria. These decisions were reached
at the 2016 Combined Policy Meeting on
Admissions to Universities, Polytechnics and other
higher institutions in Nigeria.
The Minister of Education , Malam Adamu Adamu,
while declaring open the meeting, said since the
federal government and stakeholders had
confidence in the examinations conducted by the
Joint Admissions and Matriulation Board, JAMB,
there was no need for other examinations to be
conducted by universities after JAMB exams.
He said: “As far as I am concerned, the nation has
confidence in what JAMB is doing, the universities
should not be holding another examinations and if
the universities have any complain against JAMB,
let them bring it and then we address it".
”But if JAMB is qualified enough to conduct tests
and they have conducted test, then there will be no
need to conduct another test for students to gain
admission".FG SCRAPS P.UTME