The light-emitting device comprises a substrate, an active region and a tunnel junction structure. The substrate comprises gallium arsenide. The active region comprises an n-type spacing layer and a p-type spacing layer. The tunnel junction structure comprises a p-type tunnel junction layer adjacent the p-type spacing layer, an n-type tunnel junction layer and a tunnel junction between the p-type tunnel junction layer and the n-type tunnel junction layer. The p-type tunnel junction layer comprises a layer of a p-type first semiconductor material that includes gallium and arsenic. The n-type tunnel junction layer comprises a layer of an n-type second semiconductor material that includes indium, gallium and phosphorus. The high dopant concentration attainable in the second semiconductor material reduces the width of the depletion region at the tunnel junction and increases the electrostatic field across the tunnel junction, so that the reverse bias at which tunneling occurs is reduced.
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