We obtain undopedn‐type GaSb epilayers by low‐temperature metalorganic chemical vapor deposition at a low growth temperature of 450 °C reproducibly. Different conduction types of GaSb and different energy levels are compared by photoluminescence spectra. Forn‐type undoped GaSb, the FWHM of dominant peak and bound exciton are 11 and 1.3 meV, respectively. Because semi‐insulating GaSb substrates cannot be obtained, we cannot use the Hall effect to determine the carrier concentration and mobility of the homoepilayer. In order to identify the conduction types of GaSb, ohmic contact and Schottky barrier are made by Au/Ge/Ni and Au, respectively. The concentrations of undopedn‐type GaSb homoepilayers obtained fromI‐VandC‐Vmeasurements are 1.44×1017–3.0×1017cm−3, respectively. The mobility and concentration of undopedp‐type GaSb heteroepilayers are 758 cm2/V s and 9.0×1015cm−3at 300 K, respectively.