THE N-TYPE AND P-TYPE DOPING OF GASB AND ALGASB GROWN BY METALORGANIC MOLECULAR-BEAM EPITAXY

The n-type and p-type doping characteristics are studied in the MOMBE (metalorganic molecular beam epitaxy) growth of GaSb and AlGaSb. Unintentionally doped GaSb and AlGaSb show p-type conduction. Higher hole concentration GaSb layers are obtained for lower growth temperatures and higher Sb flux. Highly p-doped (> 10(18) cm(-3)) AlGaSb layers are obtained, especially for high Al mole fraction (> 25%), due to the uptake of carbon generated by the decomposition of the metalorganic sources (triethylgallium). n-Type GaSb and AlGaSb layers are grown using GaTe as a dopant source. High electron concentrations above 2 x 10(18) cm(-3) are obtained. SIMS (secondary ion mass spectrometry) measurements show that the activation energy for the incorporation of Te into GaSb is 1.83 eV. This value is different from that in elemental source MBE with the same GaTe as a Te source. This difference is discussed in relation to the growth mechanism.