Radiative Recombinations in be-Doped Alx Ga1-x As

Abstract

Six types of systematic photoluminescence (PL) surements (T ≥ 77 K) were carried out on single crystals of Al_xGa_1-xAs (x ~ 0.3) undoped or doped with Be by LPE or ion implantation. The multimea-surements approach was employed in order to ascertain that the highest-energy radiative recombination was in fact band-to-band (BTB), and consequently to obtain accurate activation energies. LPE doped crystal luminescence consisted of a high-energy BTB peak and a lower energy shoulder (observed near 77K) assigned to free electron to bound (FTB) hole reconbination at the Be acceptor center. All Be implanted Al_xGa_1-xAs specimens had BTB radiative recombinations at T ≥ 77 K. The lower energy FTB shoulder, observed between 85 and 77K, appeared only for crystals annealed at or above 800°C, i.e., the higher temperatures are necessary to activate the implanted Be dopant in Al_xGa_l-xAs. In addition to the BTB and FTB peaks, a PL peak at ~ 1.29 eV is attributed to implantation damaqe.