Deep electron traps in organometallic vapor phase grown AlGaAs

Deep electron traps have been studied by means of deep level transient spectrosocopy in type nominally undoped and interntionally te doped Al Ga As epitaxial layers which were grown by vapor phase epitaxy from organometallic compounds (OMVPE). Three main deep electron levels are present in undoped material: a trap with an activation energy of 0.8 v, which is also foundin GaAs grown by conventional VPE, and two levels specific to OMVPE with activation energies of 0.32 and 0.38 eV, respectively. The concentration of the 0.8 V level is found to be independent of the aluminum content x, supporting the assumption that it is not related to substitutional oxygen. The other levels however, exhibit a very strong dependence of concentration on the composition, varying by four orders of magnitude in the range of in Te-doped samples, a level with an activation energy of 0.23 V has been identified, which is thought to be related to an IR emission found in photoluminescence in OMVPE as well as in liquid phase epitaxial material.