Graduate Attributes (Southern Cross University, Australia) The graduates of the University are expected to develop the following during their programmes:  Intellectual rigour  Creativity  Ethical understanding, sensitivity, commitment  Command an area of knowledge  Lifelong learning --- ability of independent & self-directed learning  Effective communication and social skills  Cultural awareness (From: S. Yeo, CDTLink, NUS, July 2004)

Importance of Materials Processing  All electronic devices & systems are made of materials in various combinations  Raw materials are far from the final electronic products  Semiconductor materials (e.g., Si, Ge, GaAs, GaN...) used for devices must be of extremely high purity and crystalline order

Desirable Device Qualities  Strong functionality  Reliable, long lifetime  Low cost, high energy efficiency  Small volume, light weight...  Examples: your notebook PC, mobile phone… All these require high precision and efficient materials processing technologies

Real Materials and their Processing  Particles, lines and rigid bodies vs. real materials  Material-specific properties determine the function and processing details of a material  Comprehensive knowledge of materials processing requires ~ 5-10 years of learning and practice  Advantage and role of physics students

Insulators, Conductors, Semiconductors from energy band structures E valence band filled conduction band empty Forbidden region E g > 5eV Band gap E conduction band E g < 5eV Band gap + - electron hole E valence band partially-filled band Insulator Semiconductor Conductor Si: E g = 1.1 eV Ge: E g = 0.75 eV GaAs: E g = 1.42 eV SiO 2 : E g = 9 eV

Electrons and Holes in Semiconductor Intrinsic semiconductor Carriers come from valence electron excitation Doped semiconductor N type P type Key: Effective control of charge carriers

Carrier type, density & mobility determined in Hall measurements JxJx B VHVH EyEy Longitudinal conductance: J x =  E x = e(n  e + p  h )E x Longitudinal resistivity:  = 1/  The Hall coefficient: If electron is the dominant carrier in the material, then we have:  = 1/  = (en  e ) -1, and Carrier density: n = -(eR H ) -1, and the mobility:  e = - R H / 

Light Emission in Semiconductors E conduction band Band gap + - electron valence band Si: E g = 1.1 eV, = 1100 nm GaAs: E g = 1.4 eV, = 873 nm AlAs: E g = 2.23 eV, = 556 nm hole h Electron-hole recombination Si: indirect bandgap, ineffective GaAs: direct bandgap, effective

Basic semiconductor devices pn Diode pn Bipolar transistor p E C B Metal-semiconductor contacts p+p+ p+p+ n SD G G Junction field-effect transistor (JFET) p n+n+ n+n+ GSiO 2 Depletion region Metal-oxide-semiconductor FET (MOSFET) Inversion region SD

Real Device Structures in IC MOSFET Bipolar transistor Diode n n+n+ p metal contacts