Light emitting diodes (LED) of an unconventional structure using lateral p-n junctions have been studied. The lateral p-n junctions can be formed by taking advantage of the crystal orientation-dependent amphoteric nature of the silicon dopant in GaAs. In this research, the lateral p-n junctions were fabricated with Si-doped GaAs epilayers grown by molecular beam epitaxy (MBE) on GaAs (111)A and (311)A-oriented substrates which were patterned before growth to alternately expose slopes of different orientations. Three MBE layer structures have been proposed. The most simple structure with only a Si-doped GaAs single layer was formed on a (311)A-oriented substrate. Secondly, a Si-doped GaAs/AlGaAs multiple quantum well (MQW) structure was fabricated on both (311)A and (111)A-oriented substrates. The third MBE layer structure consisted of an InGaAs/Si-doped GaAs single quantum well (SQW) on a (311)A-oriented substrate. The electroluminescence characteristics observed from the MQW LED fabricated on a (311)A surface showed the strongest light output power at room temperature. Thus the MQW structure was proven to be superior to the single layer structure, and the (311)A surface was found to be more suitable than the (111)A surface for lateral p-n junction LEDs. In addition, the LED using an InGaAs SQW showed light emission at a longer wavelength than the GaAs LEDs, demonstrating the different light emission wavelengths obtainable by simply changing the material and structure of the MBE layers forming the lateral p-n junction.