Mechanism of arsenic incorporation and electrical properties in CdTe layers grown by metalorganic vapor phase epitaxy

Abstract

The As doping mechanism in (100) CdTe layers grown on ( 100) GaAs by atmosphericpressure metalorganic vapor phase epitaxy was studied. Triethylarsine (TEAS) was used as a dopant source. The source materials used were dimethylcadmium (DMCd) and diethyltelluride (DETe) . The As incorporation was enhanced by decreasing the DETe flow rate under a fixed DMCd flow condition, and by lowering the growth temperature. Assuming 100% activation of As, the As incorporation efficiency was estimated to be about 0.1%. The As incorporation was dominated by the sticking rate of the As species onto the Cd species. The hole concentration was controlled from 2x 1015 to 3 x lOi cm -3 in proportion to the TEAS flow rate below 1 x lo-' mol/min. Those doped layers showed hole mobilities as high as 75 cm2/V s. Low-temperature photoluminescence (PL) studies revealed that a neutral-acceptor bound-exciton at 1.5901 eV is due to a substitutional As acceptor on the Te site. The As ionization energy was about 90 meV from the PL and electrical measurements.

Electrical and optical properties of lodine doped CdZnTe layers grown by metalorganic vapor phase epitaxy

“…For the CdTe layer, on the other hand, the strain was estimated to be ε = 2.81 × 10 -4 where X HH = 1.5962 eV and X LH = 1.5978 eV were employed which were obtained previously for the CdTe layers with the similar thickness. 8 The obtained strain magnitudes are similar to the reported values previously. 11 Using these strain magnitudes and assuming the energy 16 Thus, the energy band gap of GaAs is estimated to be 7.6 meV larger for the ZnTe growth than for the CdTe growth.…”

“…Since these spectra are similar to those observed previously for high quality As doped CdTe layers grown on GaAs at 375°C, the (A 0 X) line is attributed to the As acceptor which was incorporated from the GaAs substrate during the growth. 8 Also, the (A 0 ,X) line was observed at slightly higher energy region than that observed previously. The energy shift was considered due to larger compressive strain induced in the CdTe layer grown in this experiment (at 450°C) than that of grown at 375°C previously.…”

“…The tensile strain is due to the larger thermal expansion coeffecient of ZnTe than that of GaAs substrate. 8 A weak emission line was also observed at 2.3564 eV. This emission line coincides with the (A 0 ,X) line which has been assigned as a neutral carbon acceptor bound exciton emission.…”

“…The DAP band is also considered due to the iodine donor and some deep acceptors such as Ag or Cu rather than the As acceptor, since the zero phonon emission line of the DAP band is estimated to locate at around 1.507 eV for iodine donors and As acceptors. 8 Lee et al observed a sharp emission at 1.491 eV followed by a broad DAP emission at the low energy region in the heavily iodine doped CdTe layer grown on CdTe substrate. 9 They also proposed a mechanism of this emission, however, the proposed emission mechanism may not be applied to our CdTe layers since layers were grown on GaAs substrates.…”

Акцепторное легирование мышьяком при осаждении слоев CdTe из диметилкадмия и диизопропилтеллура

“…Курицын лять концентрацией собственных дефектов и изменять условия вхождения примеси в слои за счет использования разнообразных прекурсоров и их соотношений. В качестве источников примеси мышьяка в методе MOCVD применяют арсин и его производные [10][11][12], а в последнее время наибольшее применение находит трис-диметила-миноарсин (ТДМАА, TDMAAs, As[N(CH 3 ) 2 ] 3 ) [6,[13][14][15][16]. Это связано с его невысокой температурой распада (50% при 350 • С [17]), а также низким давлением пара, что обеспечивает лучший контроль уровня легирования.…”