LATERAL P-N-JUNCTIONS ON GAAS(111)A SUBSTRATES PATTERNED WITH EQUILATERAL TRIANGLES

We report the successful formation of lateral p-n junctions by molecular beam epitaxy (MBE) of Si-doped GaAs on (111)A substrates patterned with equilateral triangles. The idea of lateral p-n junctions with a triangular p-type region encircled with three crystallographically equivalent n-type slopes is based on the three-fold symmetry of the (111)A surface and the acceptor nature of the dopant Si on the (111)A surface in contrast to the donor on surfaces with the other orientations. Bad surface morphologies of layers grown on the (111)A surface have been a barrier against practical applications of this surface. We have successfully improved the (111)A surface morphology by pre-growth thermal cleaning, at both higher temperatures and higher As pressures. The formation of lateral p-n junctions is confirmed by spatially resolved cathodoluminescence measurements. This lateral p-n junction can be applied to structures that demand lateral carrier confinement, such as surface emitting laser diodes.