Sharp Kabushiki Kaisha Corporation

Katherine L Johnson

Jonathan Heffernan

Stewart Edward Hooper

Valerie Bousquet

Matthias Kauer

Jennifer Mary Barnes

A method of fabricating a continuous wave semiconductor laser diode in the (Al,Ga,In)N materials system comprises: growing, in sequence, a first cladding region (), a first optical guiding region (), an active region (), a second optical guiding region () and a second cladding region (). Each of the first cladding region (), the first optical guiding region (), the active region (), the second optical guiding region () and the second cladding region () is deposited by molecular beam epitaxy.

MBE growth of a semiconductor laser diode

A method of growing a p-type nitride semiconductor material by molecular beam epitaxy (MBE) uses bis(cyclopentadienyl)magnesium (Cp2Mg) as the source of magnesium dopant atoms. Ammonia gas is used as the nitrogen precursor for the MBE growth process. To grow p-type GaN, for example, by the method of the invention, gallium, ammonia and Cp2Mg are supplied to an MBE growth chamber; to grow p-type AlGaN, aluminum is additionally supplied to the growth chamber. The growth process of the invention produces a p-type carrier concentration, as measured by room temperature Hall effect measurements, of up to 2 1017 cm&#x2212;3, without the need for any post-growth step of activating the dopant atoms.

MBE growth of p-type nitride semiconductor materials

A method of manufacturing a semiconductor light-emitting device comprises selectively etching a semiconductor layer structure () fabricated in a nitride materials system and including an aluminum-containing cladding region or an aluminum-containing optical guiding region (). The etching step forms a mesa (), and also exposes one or more portions of the aluminum-containing cladding region or the aluminum-containing optical guiding region (). The or each exposed portion of the aluminum-containing cladding region or the aluminum-containing optical guiding region () is then oxidized to form a current blocking layer () laterally adjacent to and extending laterally from the mesa. When an electrically conductive contact layer () is deposited, the current blocking layer () will prevent the contact layer () from making direct contact with the buffer layer ().

Semiconductor light-emitting device and a method of manufacture thereof

A method of growing an AlGaN semiconductor layer structure by Molecular Beam Epitaxy comprises supplying ammonia, gallium and aluminum to a growth chamber thereby to grow a first (Al,Ga)N layer by MBE over a substrate disposed in the growth chamber. The first (Al,Ga)N layer has a non-zero aluminum mole fraction. Ammonia is supplied at a beam equivalent pressure of at least 1 10mbar, gallium is supplied at a beam equivalent pressure of at least 1 10mbar and aluminum is supplied at a beam equivalent pressure of at least 1 10mbar during the growth step. Once the first (Al,Ga)N layer has been grown, varying the supply rate of gallium and/or aluminum enables a second (Al,Ga)N layer, having a different aluminum mole fraction from the first (Al,Ga)N layer to be grown by MBE over the first (Al,Ga)N layer. This process may be repeated to grown an (Al,Ga)N multilayer structure.

MBE growth of an algan layer or AlGaN multilayer structure

A semiconductor light-emitting device fabricated in a nitride material system has an active region disposed over a substrate. The active region comprises a first aluminium-containing layer forming the lowermost layer of the active region, a second aluminium-containing layer forming the uppermost layer of the active region, and at least one InGaN quantum well layer disposed between the first aluminium-containing layer and the second aluminum-containing layer. The aluminium-containing layers provide improved carrier confinement in the active region, and so increase the output optical power of the device.

Semiconductor light-emitting device having an active region with aluminum-containing layers forming the lowermost and uppermost layer

A method of fabricating the active region of a semiconductor light-emitting device, in which the active region comprises a plurality of barrier layers () with each pair of barrier layers being separated by a quantum well layer (), comprises annealing each barrier layer () separately. Each barrier layer () is annealed once it has been grown, and before a layer is grown over the barrier layer. A device grown by the method of the invention has a significantly higher optical power output than a device made by a convention fabrication process having a single annealing step.

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Oxford, United Kingdom

Katherine L Johnson