Band Structure
Physical alteration of the electronic energy levels in a semiconductor crystal arises from mechanical strain, lattice defects, or external electrostatic fields. This energy band deformation alters the bandgap, which changes the electrical and optical properties of the material. It shifts the positions of the conduction and valence band edges relative to each other.
Such a modification affects carrier mobility, recombination rates, and the operating characteristics of semiconductor devices. Developers utilize this effect in strained silicon technology to enhance transistor performance in modern integrated circuits.
Strain Mechanism
Mechanical stress applied to the crystalline lattice changes the atomic spacing and breaks the symmetry of the crystal. Through this mechanism, energy band deformation occurs locally and shifts the effective mass of the charge carriers. This shift decreases the scattering rate and allows electrons or holes to travel faster through the semiconductor channel.
Device Output
Unintended stress from packaging or thermal expansion mismatches can degrade sensor accuracy and transistor performance. In high-precision analog electronics, local energy band deformation modifies the piezoresistive behavior and introduces offset voltage drift. Engineers must analyze these mechanical stresses during the packaging design phase to prevent drift in sensitive sensor components.
Metrology Scan
Optical spectroscopy and micro-Raman measurements allow researchers to detect the localized strain within the silicon structure. These non-destructive measurement techniques correlate the shift in lattice vibration frequencies with the intensity of the energy band deformation. By mapping these changes across the wafer surface, semiconductor fabs can optimize the manufacturing process to minimize unwanted strain.
