GaAs buried growth over tungsten stripe using TEG and TMG

We studied the buried growth of a GaAs layer over a tungsten stripe using o rganometallic vapor-phase epitaxy. Triethylgallium (TEG) and trimethylgalli um (TMG) were used as group III sources. For growth without polycrystal-lik e deposition on tungsten surface, the required growth temperature using TMG was lower than that using TEG. For 2-mum-thick growth over a 1-mum-wide tu ngsten stripe, the flatness of the surface grown using TMG was better than that using TEG. Therefore, the migration length of TMG on tungsten and GaAs must be longer than that of TEG. For a heterojunction bipolar transistor w ith a tungsten stripe as the collector electrode, a 70-nm-wide tungsten str ipe was buried under a 0.77-mum-thick layer of GaAs with a flat surface usi ng TMG. A current gain of 4 was measured although the active region was gro wn over tungsten stripe. (C) 2000 Elsevier Science B.V. All rights reserved .