The Secretary of State for Defence in Her Britannic Majesty's Government

The Secretary of State for Defence in Her Britannic Majesty's Government of the United Kingdom of Great Britain and Northern Ireland

Weng Y Leong

John M Keen

Leigh-Trevor Canham

Leigh Trevor Canham

Timothy I Cox

Surjit S Chadha

Michael S Waite

A method of making semiconductor quantum wires employs a semiconductor wafer ( ) as starting material. The wafer ( ) is weakly doped p type with a shallow heavily doped p layer therein for current flow uniformity purposes. The wafer ( ) is anodised in 20% aqueous hydrofluoric acid to produce a layer ( ) microns thick with 70% porosity and good crystallinity. The layer is subsequently etched in concentrated hydrofluoric acid, which provides a slow etch rate. The etch increases porosity to a level in the region of 80% or above. At such a level, pores overlap and isolated quantum wires are expected to form with diameters less than or equal to 3 nm. The etched layer exhibits photoluminescence emission at photon energies well above the silicon bandgap (1.1 eV) and extending into the red region (1.6-2.0 eV) of the visible spectrum.

Silicon quantum wires

##STR1## A method of making semiconductor quantum wires employs a semiconductor wafer (14) as starting material. The wafer (14) is weakly doped p type with a shallow heavily doped p layer therein for current flow uniformity purposes. The wafer (14) is anodised in 20% aqueous hydrofluoric acid to produce a layer (5) microns thick with 70% porosity and good crystallinity. The layer is subsequently etched in concentrated hydrofluoric acid, which provides a slow etch rate. The etch increases porosity to a level in the region of 80% or above. At such a level, pores overlap and isolated quantum wires are expected to form with diameters less than or equal to 3 nm. The etched layer exhibits photoluminescence emission at photon energies well above the silicon bandgap (1.1 eV) and extending into the red region (1.6-2.0 eV) of the visible spectrum.

Method of making silicon quantum wires

A method of making semiconductor quantum wires, and a light emitting device employing such wires, employs a semiconductor wafer as starting material. The wafer is weakly doped p type with a shallow heavily doped p layer therein for current flow uniformity purposes. The wafer is anodized in 20% aqueous hydrofluoric acid to produce a layer 5 microns thick with 70% porosity and good crystallinity. The layer is subsequently etched in concentrated hydrofluoric acid, which provides a slow etch rate. The etch increases porosity to a level in the region of 80% or above. At such a level, pores overlap and isolated quantum wires are expected to form with diameters less than or equal to 3 nm. When excited, the etched layer exhibits photoluminescence emission at photon energies well above the silicon bandgap (1.1 eV) and extending into the red region (1.6-2.0 eV) of the visible spectrum.

Electroluminescent silicon device

A method of making semiconductor quantum wires employs a semiconductor wafer (14) as starting material. The wafer (14) is weakly doped p type with a shallow heavily doped p layer therein for current flow uniformity purposes. The wafer (14) is anodised in 20% aqueous hydrofluoric acid to produce a layer (5) microns thick with 70% porosity and good crystallinity. The layer is subsequently etched in concentrated hydrofluoric acid, which provides a slow etch rate. The etch increase porosity to a level in the region of 80% or above. At such a level, pores overlap and isolated quantum wires are expected to from with diameter less than or equal to 3 nm. The etched layer exhibits photoluminescence emission at photon energies well above the silicon bandgap (1.1 eV) and extending into the red region (1.6-2.0 eV) of the visible spectrum.

A direct current electroluminescent device having a phosphor layer and coating electrodes, at least one of which is translucent, which has interposed between the phosphor layer and at least one of said electrodes a thin non-planar layer of an electrically non-conducting substance. The non-planar layer may have a cross section of undulating outline or may be a discontinuous layer, e.g. in the form of closely spaced dots. Preferably the non-planar layer is translucent and is arranged between the phosphor layer and a translucent electrode. Suitable materials for the non-planar layer include silicon monoxide, silicon dioxide, germanium dioxide, magnesium fluoride, cadmium fluoride, yttrium fluoride, yttrium oxide, zinc sulphide, copper sulphide.

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Weng Y Leong