Thep‐type nature of unintentionally doped GaSb molecular beam epitaxy grown layers has been attributed to native defects resulting from insufficient Sb incorporation. As a means to improve the quality of GaSb epilayers, growth on (311) Bsubstrates was studied and shown to produce Te‐doped GaSb layers with room‐temperature mobilities of 6780 cm2/V s at carrier densities of 9×1015cm−3and AlGaSb/GaSbp‐i‐ndiode structures with breakdown voltages as high as 20 V. These mobilities and breakdown voltages are the highest achieved for molecular beam epitaxy grown GaSb‐based structures.