The structure and properties of metal-semiconductor interfaces

https://aziz.seas.harvard.edu/files/mja026.pdf

Continuous growth model for interface motion during alloy solidification

An object is to provide a method for manufacturing a semiconductor device, in which the number of photolithography steps can be reduced, the manufacturing process can be simplified, and manufacturing can be performed with high yield at low cost A method for manufacturing a semiconductor device includes the following steps: forming a semiconductor film; irradiating a laser beam by passing the laser beam through a photomask including a shield for shielding the laser beam; subliming a region which has been irradiated with the laser beam through a region in which the shield is not formed in the photomask in the semiconductor film; forming an island-shaped semiconductor film in such a way that a region which is not irradiated with the laser beam is not sublimed because it is a region in which the shield is formed in the photomask; forming a first electrode which is one of a source electrode and a drain electrode and a second electrode which is the other one of the source electrode and the drain electrode; forming a gate insulating film; and forming a gate electrode over the gate insulating film

Method for Manufacturing Semiconductor Device

We observe an insulator-to-metal transition in crystalline silicon doped with sulfur to nonequilibrium concentrations using ion implantation followed by pulsed-laser melting and rapid resolidification. This insulator-to-metal transition is due to a dopant known to produce only deep levels at equilibrium concentrations. Temperature-dependent conductivity and Hall effect measurements for temperatures $Tg1.7\text{ }\text{ }\mathrm{K}$ both indicate that a transition from insulating to metallic conduction occurs at a sulfur concentration between 1.8 and $4.3\ifmmode\times\else\texttimes\fi{}{10}^{20}\text{ }\text{ }{\mathrm{cm}}^{\ensuremath{-}3}$. Conduction in insulating samples is consistent with variable-range hopping with a Coulomb gap. The capacity for deep states to effect metallic conduction by delocalization is the only known route to bulk intermediate band photovoltaics in silicon.

https://aziz.seas.harvard.edu/files/mja211.pdf

Insulator-to-Metal Transition in Sulfur-Doped Silicon

A very thin gold coating (e.g., 270 to 3,500 Angstroms) is vapor deposited on the surface of a nickel substrate. A short radiant energy pulse from a laser having a pulse length of about 130 nanoseconds is directed at the coated surface to melt portions of the gold coating and the nickel substrate therebelow. The energy pulse is removed to permit the melted material to resolidify as an alloy with a high concentration of gold at the surface thereof.

Laser surface alloying

The formation of supersaturated substitutional alloys by ion implantation and rapid liquid‐phase‐epitaxial regrowth induced by pulsed laser annealing has been studied using Rutherford backscattering, ion channeling analysis. Group‐III (Ga, In) and group‐V (As, Sb, Bi) dopants have been implanted into single‐crystal silicon at doses ranging from 1×1015 to 1×1017/cm2. The samples were annealed with a Q‐switched ruby laser (energy density ∼1.5 J/cm2, pulse duration ∼15×10−9 sec). Ion channeling analysis shows that laser annealing incorporates these dopants into substitutional lattice sites at concentrations far in excess of the equilibrium solid solubility. Channeling measurements indicate the silicon crystal is essentially defect free after laser annealing. Also values for the maximum dopant concentration (Cmaxs) that can be incorporated into substitutional lattice sites are determined for our annealing conditions. Dopant profiles determined by Rutherford backscattering are compared to model calculations wh...

Supersaturated substitutional alloys formed by ion implantation and pulsed laser annealing of group-III and group-V dopants in silicon

Group III and V dopants are highly substitutional in silicon after laser annealing even when the concentration exceeds the solubility limit. These alloys exhibit retrograde solubility in Si and this confirms the nonequilibrium nature of the liquid phase epitaxial regrowth process. Maximum values for substitutional solubility after laser annealing have been measured and correlated with the onset of constitutional supercooling. Thermal annealing of supersaturated alloys allows the equilibrium solubility limit to be determined.

F. W. Young

Papers

Supersaturated substitutional alloys formed by ion implantation and pulsed laser annealing of group-III and group-V dopants in silicon

Supersaturated substitutional alloys in silicon formed by ion implantation and laser annealing

Borrmann topographic investigation on dislocation configuration in well-annealed and lightly deformed copper crystals