Lesson_1.pdf

Lesson 1

Assoc. Professor Hovik Baghdasaryan

Head of Fiber Optics Communication Laboratory

State Engineering University of Armenia

Yerevan, Armenia

“Fundamentals of Electronics and Photonics”

I. What is Electronics?

Electronics refers to the flow of charges through conducting and semi-conducting materials.

Our interest is in Solid State Electronics, namely Semiconductor Electronics.

and a lot of others.

II.

What is Photonics?

Photonics is the science of generating, controlling, and detecting photons. This is particularly done

in the visible and near-infrared ranges of the electromagnetic spectrum but may also extend to the

ultraviolet (0.2–0.35µm wavelength), long-wave infrared (8–12µm wavelength), and far-

infrared/THz (e.g., 2-4 THz corresponding to 75–150 µm wavelength) portions of the spectrum.

Figure 1from S.M. Sze, K.K.Ng. (page 602)

Photonics developed as an outgrowth of the first practical semiconductor light emitters

invented in the early 1960s and optical fibers developed in the 1970s.

An optical fiber communication link.

The field of Photonics, sometimes referred to as optical electronics. The last two-word term

indicate complex devices having an optical and electronic features to generate light by current, to

detect light by transferring it to current and a lot of other photo-electronic characteristics, mainly

made of semiconductor or crystalline devices.

For Electronics an important feature is the conductivity of materials, namely, conductivity of

solid-state materials:

Non-conductive materials

(Dielectrics or insulators)

Semi-conductive materials

(Semiconductors)

Conductive materials

(Metals)

Our interest mainly will be directed towards the physics of semi-conductors, most widely used

materials in Electronics and Photonics.

Following to B.G. Streetman

1.1 Semiconductor materials

Semiconductors are a group of materials having electrical conductivities intermediate between metals

and insulators. It is significant that the conductivity of these materials can be varied over orders of

magnitude by changes in temperature, optical excitation, and impurity content. This variability of

electrical properties makes the semiconductor materials natural choices for electronic and opto-

electronic devices.

Semiconductor materials are found in column IV and neighboring columns of the periodic table

(Table 1-1). The column IV semiconductors, silicon and germanium, are called elemental

semiconductors because they are composed of single species of atoms. In addition to the elemental

materials, compounds of column III and column V atoms, as well as certain combinations from II and

VI, make up the inter-metallic, or compound, semiconductors.

TABLE 1-1. Common semiconductor materials: (a) the portion of the periodic table where semiconductors

occur; (b) elemental and compound semiconductors.

(a)

III

(b)

Elemental IV compounds Binary III-V

compaunds

Binary II-

compounds

Si SiC A1P

ZnS

SiGe

AlAs

ZnSe

AlSb

ZnTe

GaP

CdS

GaAs

CdSe

GaSb

CdTe

InP

InAs

InSb

As Table 1-1 indicates, there are numerous semiconductor materials. As we shall see, the wide

variety of electronic and optical properties of these semiconductors provides the device engineer

with great flexibility in the design of electronic and optoelectronic functions. The elemental

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