Alternative Boron Precursors for BGaAs Epitaxy

The organometallic vapor phase epitaxy growth of zinc-blende B_xGa_1-xAs and B_xGa_1-x-yIn_yAs with boron concentrations (x) up to 3-5% has recently been demonstrated using diborane as a boron precursor. Growth of these alloys using diborane is complicated by many factors, such as parasitic gas-phase reactions, highly temperature-dependent boron incorporation, and limited boron incorporation before the onset of structural breakdown. These factors suggest that diborane may not be the best precursor for the growth of these alloys. We compare the use of alternative boron precursors; trimethylboron (TMB), triethylboron (TEB), and boron trifluoride (BF₃), with diborane for the OMVPE growth of these boron containing III-V alloys. We find that TMB and BF₃ do not result in significant boron incorporation into GaAs. TEB does result in boron incorporation in a manner very similar to diborane. Both diborane and TEB incorporate more efficiently using triethylgallium (TEG) rather than trimethylgallium (TMG), making TEG a preferred source of gallium for BGaAs epitaxy. Using TEB together with TEG, a higher boron composition (x = 4-7%) has been achieved than has been previously reported, but the complicating problems observed with diborane still exist.