Sharp Kabushiki Kaisha Corporation

Jennifer Mary Barnes

Jonathan Heffernan

Stewart Edward Hooper

Valerie Bousquet

Alistair Henderson Kean

Katherine L Johnson

Wei-Sin Tan

A laser diode structure that includes two different insulator layers, one to maintain good optical confinement, typically located at the sides of the laser ridge, and another to improve the heat dissipation properties, typically located on the etched surfaces away from the ridge.

Laser diode with improved heat dissipation

A method of MBE growth of a semiconductor layer structure comprises growing a first (Al,Ga)N layer (step) over a substrate at the first substrate temperature (T) using ammonia as the nitrogen precursor. The substrate is then cooled (step) to a second-substrate temperature (T) which is lower than the first substrate temperature. An (In,Ga)N quantum well structure is then grown (step) over the first (Al,Ga)N layer by MBE using ammonia as the nitrogen precursor. The supply of ammonia to the substrate is maintained continuously during the first growth step, the cooling step, and the second growth step. After completion of the growth of the (In,Ga)N quantum well structure, the substrate may be heated to a third temperature (T) which is greater than the second substrate temperature (T). A second (Al,Ga)N layer is then grown over the (In,Ga)N quantum well structure (step).

MBE growth of a semiconductor layer structure

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 method of growing a p-type nitride semiconductor material having magnesium as a p-type dopant by molecular beam epitaxy (MBE), comprises supplying ammonia gas, gallium and magnesium to an MBE growth chamber containing a substrate so as to grow a p-type nitride semiconductor material over the substrate. Magnesium is supplied to the growth chamber at a beam equivalent pressure of at least 1 10-9 mbar, and preferably in the range from 1 10-9 mbar to 1 10-7 mbar during the growth process. This provides p-type GaN that has a high concentration of free charge carriers and eliminates the need to activate the magnesium dopant atoms by annealing or irradiating the material.

Method of growing a semiconductor layer

The invention provides a method of growing an (In, Ga)N multiplayer structure by molecular beam epitaxy. Each GaN or InGaN layer in the multilayer structure is grown at a substrate temperature of at least 650&#xb0; C., and this provides improved material quality. Ammonia gas is used as the source of nitrogen for the growth process. Ammonia and gallium are supplied to the growth chamber at substantially constant rates, and the supply rate of indium to the growth chamber is varied to select the desired composition for the layer being grown. This allows the structure to be grown at a substantially constant growth rate. The substrate temperature is preferably kept constant during the growth process, to avoid the need to interrupt the growth process to vary the substrate temperature between the growth of one layer and the growth of another layer.

Method of growing a semiconductor multi-layer structure

This invention relates to a method of growing a nitride semiconductor layer by molecular beam epitaxy comprising the steps of: a) heating a GaN substrate (S) disposed in a growth chamber ( ) to a substrate temperature of at least 850&deg; C.; and b) growing a nitride semiconductor layer on the GaN substrate by molecular beam epitaxy at a substrate temperature of at least 850&deg; C., ammonia gas being supplied to the growth chamber ( ) during the growth of the nitride semiconductor layer; wherein the method comprises the further step of commencing the supply ammonia gas to the growth chamber during step (a), before the substrate temperature has reached 800&deg; C.

A method of growing a nitride semiconductor layer, such as a GaN layer, by molecular beam epitaxy comprises the step of growing a GaAlN nucleation layer on a substrate by molecular beam epitaxy. The nucleation layer is annealed, and a nitride semiconductor layer is then grown over the nucleation layer by molecular beam epitaxy. The nitride semiconductor layer is grown at a V/III molar ratio of 100 or greater, and this enables a high substrate temperature to be used so that a good quality semiconductor layer is obtained. Ammonia gas is supplied during the growth process, to provide the nitrogen required for the MBE growth process.

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Oxford, United Kingdom

Jennifer Mary Barnes