NOVELTY - The device comprises a first base region (102) comprising an n-type III-V semiconductor material, a second base region (104) comprising a p-type III-V semiconductor material, and a multi-quantum well structure arranged between the first base region and the second base region. A first barrier region of the well structure is arranged between a first quantum well region (108) and a second quantum well region (110) of the well structure. A second barrier region of the well structure is arranged between the second quantum well region and a third quantum well region (112) of the well structure.    USE - The radiation-emitting semiconductor device is useful as an LED device (claimed), semiconductor lasers, photo detectors and solar cells.    ADVANTAGE - The device reduces discrepancy between mobility of electrons and electron holes in the III-V semiconductor materials thus providing uniform distribution of electrons and electron-holes within the active regions of the device, and is fabricated with thick layers of crystalline III-V semiconductor material having relatively low concentrations of defects.    DETAILED DESCRIPTION - The device comprises a first base region (102) comprising an n-type III-V semiconductor material, a second base region (104) comprising a p-type III-V semiconductor material, and a multi-quantum well structure arranged between the first base region and the second base region. A first barrier region of the multi-quantum well structure is arranged between a first quantum well region (108) and a second quantum well region (110) of the multi-quantum well structure. A second barrier region of the multi-quantum well structure is arranged between the second quantum well region and a third quantum well region (112) of the multi-quantum well structure. The first quantum well region is located closer to the first base region than the third quantum well region. The third quantum well region is located closer to the second base region than the first quantum well region. Each of the first quantum well regions, the second quantum well region and the third quantum well region has a well region thickness of 20 nm in a direction extending between the first base region and the second base region. Each of the first barrier region and the second barrier region has a barrier region thickness in the direction extending between the first base region and the second base region greater than or equal to each of the well region thicknesses. An electron hole energy barrier between the third quantum well region and the second quantum well region is less than an electron hole energy barrier between the second quantum well region and the first quantum well region. Each of the first quantum well regions, the second quantum well region and the third quantum well region comprises a ternary III-nitride material. Each of the first barrier region and the second barrier region comprises a ternary III-nitride material. Each of the first barrier region and the second barrier region comprises a binary III-nitride material. The first barrier region has a first band gap energy, and the second barrier region has a second band gap energy. The second band gap energy is less than the first band gap energy. The multi-quantum well structure further comprises additional quantum well regions and additional barrier regions. The electron hole energy barriers between adjacent quantum well regions in the multi-quantum well structure decrease in a step-wise manner across the multi-quantum well structure from the first base region to the second base region. An INDEPENDENT CLAIM is included for a method for forming a radiation-emitting device.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic cross-sectional view of a radiation-emitting semiconductor device and a corresponding energy band diagram for the device.    First base region (102)    Second base region (104)    First quantum well region (108)    Second quantum well region (110)    Third quantum well region. (112)