Abstract: A group III nitride-based light emitting device includes an n-type group III nitride-based semiconductor layer, a p-type group III nitride-based semiconductor layer, and a group III nitride-based active region between the p-type semiconductor layer and the n-type semiconductor layer. The active region includes a plurality of sequentially stacked group III nitride-based quantum well layers interspersed with barrier layers. A plurality of the barrier layers have a variation in composition of a first element along a growth direction within a thickness of each of the plurality of barrier layers, and the variation in composition of the first element has at least one minimum and a position of the minimum varies in the plurality of barrier layers. The first element may be indium or aluminum, and the number of barrier layers including the composition variation may be at least three barrier layers. The composition variation may vary linearly or non-linearly.

Abstract: A group III nitride-based light emitting device includes an n-type group III nitride-based semiconductor layer, a p-type group III nitride-based semiconductor layer, and a group III nitride-based active region between the p-type semiconductor layer and the n-type semiconductor layer. The active region includes a plurality of sequentially stacked group III nitride-based quantum well layers interspersed with barrier layers. A plurality of the barrier layers have a variation in composition of a first element along a growth direction within a thickness of each of the plurality of barrier layers, and the variation in composition of the first element has at least one minimum and a position of the minimum varies in the plurality of barrier layers. The first element may be indium or aluminium, and the number of barrier layers including the composition variation may be at least three barrier layers. The composition variation may vary linearly or non-linearly.

Abstract: A method of manufacturing a semiconductor device comprises depositing a semiconductor layer over a semiconductor surface having at least one first region with a first (average surface lattice) parameter value and at least one second region having a second parameter value different from the first. The semiconductor layer is deposited to a thickness so self-organized islands form over both the first and second regions. The difference in the parameter value means the islands over the first region have a first average parameter value and the islands over the second region have a second average parameter value different from the first. A capping layer is deposited over islands and has a greater forbidden bandgap than the islands whereby the islands form quantum dots, which have different properties over the first and second regions due to difference(s) between the first and second region islands.

Abstract: A semiconductor light-emitting device comprises a semiconductor layer structure disposed over a substrate. The layer structure includes an active region disposed between a first layer and a second layer. One or more cavities are present in the layer structure, each cavity being coincident with a threading dislocation and extending from an upper surface of the layer structure through at least the second layer and the active region. Removing material where a threading dislocation is present provides effective suppression of the tendency of the threading dislocations to act as non-radiative centres, thereby improving the light output efficiency of the device. The device may be manufactured by a first step of selectively etching the layer structure at the locations of one or more threading dislocation to form a pilot cavity at the or each location. A second etching step is applied to increase the depth of each pilot cavity.

Abstract: A nitride semiconductor device comprises: a layer structure including an active region (102) containing AlxGayIn1-x-yN quantum dots layers (102a), and means (104a,104b) for applying an electric field across the active region to modify the spin orientation of excitons in the quantum dots. The exciton spin lifetime at 300K is, for at least a range of values of the electric field applied across the active region, at least 1 ns, more preferably at least 10 ns, and particularly preferably at least 15 ns or 20 ns. These lifetimes may be obtained by configuring the device such that the exciton binding energy is, for at least a range of values of the electric field applied across the active region, 25 meV or greater.

Abstract: A semiconductor light-emitting device fabricated in the (Al,Ga,In)N materials system has an active region for light emission (3) comprising InGaN quantum dots or InGaN quantum wires. An AlGaN layer (6) is provided on a substrate side of the active region. This increases the optical output of the light-emitting device. This increased optical output is believed to result from the AlxGa1-xN layer serving, in use, to promote the injection of carriers into the active region.

Abstract: A photon source includes a substrate, an active region formed above the substrate, and a pair of electrodes configured to provide an injection current which passes through the active region. The active region includes a quantum dot layer including one or more AlyGaxIn1-x-yN quantum dots, where 0?x?1 and 0?y?<1, and an AlInN current confinement layer adjacent the quantum dot layer. The current confinement layer has an aperture which defines a low resistance path for the injection current to flow through the active region between the pair of electrodes. The quantum dot layer includes less than 50 quantum dots within the aperture as projected onto the quantum dot layer.

Abstract: A semiconductor device includes an AlxGayIn1-x-yN layer and (Al,Ga,In)N quantum dots disposed on the AlxGayIn1-x-yN layer, wherein the indium fraction in the AlxGayIn1-x-yN layer is non-zero (1-x-y?0).

Abstract: A method of making an (Al, Ga, In)N semiconductor device having a substrate and an active region is provided. The method includes growing the active region using a combination of (i) plasma-assisted molecular beam epitaxy; and (ii) molecular beam epitaxy with a gas including nitrogen-containing molecules in which the nitrogen-containing molecules dissociate at a surface of the substrate at a temperature which the active region is grown.

Abstract: A semiconductor light-emitting device fabricated in the (Al,Ga,In)N materials system has an active region for light emission (3) comprising InGaN quantum dots or InGaN quantum wires. An AlGaN layer (6) is provided on a substrate side of the active region. This increases the optical output of the light-emitting device. This increased optical output is believed to result from the AlxGa1-xN layer serving, in use, to promote the injection of carriers into the active region.

Abstract: A method of manufacturing a semiconductor device comprises depositing a semiconductor layer over a semiconductor surface having at least one first region with a first (average surface lattice) parameter value and at least one second region having a second parameter value different from the first. The semiconductor layer is deposited to a thickness so self-organised islands form over both the first and second regions. The difference in the parameter value means the islands over the first region have a first average parameter value and the islands over the second region have a second average parameter value different from the first. A capping layer is deposited over islands and has a greater forbidden bandgap than the islands whereby the islands form quantum dots, which have different properties over the first and second regions due to difference(s) between the first and second region islands.