The decay of the photoluminescence at 1.54 μm from erbium-implanted silicon has been recorded over nearly three decades of intensity. Two components of the decay are observed at 7.5 K, one with a decay time constant of ∼40–160 μs, and the other with a characteristic time of between 800 and 1200 μs. It is found that the proportions of fast and slow components can vary depending upon the amount of implantation-induced damage, and this variation correlates with a broadening on the high energy side of the erbium related emission. The temperature dependence of the fastest decay is not consistent with it being due to an Auger process involving free carriers, and it is suggested that extended defects in the layers are responsible for this part of the decay curve. The broadening of the erbium line is attributed to the overlap of the dislocation-related line D1 with the erbium emission. Selective chemical etching and scanning electron microscopy show that there are extended defects present in samples with a short fast decay component.
The paper briefly compares the architecture of commonly used channel sounders for single input multiple output (SIMO) and multiple input multiple output (MIMO) applications. The architecture of a novel dual UMTS band parallel receiver sounder developed for the purposes of such studies is outlined. The performance of the sounder from back-to-back measurements and calibration considerations are discussed. Outdoor SIMO measurements and indoor/outdoor MIMO measurements obtained with different antenna arrays demonstrate its capability.
Reports showing that hydrogen and group-III acceptors play an important role in Light- and elevated Temperature-induced Degradation (LeTID) of Si-based solar cells highlight the need for a better understanding of interactions between these two species. In this contribution, a combination of junction spectroscopy techniques and first principles modelling has been used to study hydrogen-induced changes in electrical properties of either boron or gallium Czochralski-grown silicon co-doped with phosphorus in order to produce n-type material facilitating novel techniques to assess recombination active defects. The interactions of hydrogen with acceptor atoms have been induced via annealing of these co-doped hydrogenated samples with the application of reverse bias (RBA). These treatments have resulted in a significant increase in the net shallow donor concentration in depletion regions of both materials and in the appearance of a strong electron emission signal due to a trap with an energy level at about Ec −0.18 eV in the DLTS spectra of Si:P + B material. It is argued that this trap is related to the donor level of a BH2 complex. Calculations using density functional theory have shown that the BH2 defect has a charge-state dependent geometry, which turns out to be crucial for the proposed non-radiative recombination mechanism. The BH2 defect is therefore suggested to be the root cause of LeTID in boron-doped Si. In contrast, modelling results predict that GaH2 is a defect with shallow energy levels, without the characteristic features of a recombination centre. This is corroborated by the results of electrical measurements on hydrogenated Si:P + Ga subjected to RBA. Conventional annealing treatments were subsequently used to assess the thermal stability of acceptor-H related defects. Based on the obtained results, the peculiarities of hydrogen interactions with boron and gallium acceptors are discussed.
For nominally identical GaN Schottky diodes prepared by resistive thermal evaporation and plasma sputter deposition, diodes prepared by sputter deposition were found to exhibit a clear increase in the reverse leakage current, which is about two orders of magnitude higher than diodes prepared using thermal evaporation. Defects in n-type GaN Schottky diodes fabricated by plasma sputtering of gold were investigated using deep-level transient spectroscopy and compared with those in similar structures fabricated by resistive thermal evaporation. From deep level transient spectroscopy two defects were identified in the sputtered diode with the activation energies for charge carrier emission of 0.26±0.01eV relative to the conduction band edge and 0.62±0.04eV relative to the valence band edge. Defect concentration profiles of sputtered diodes show the defect density reduces from the surface to deeper in the structure, indicating that they are introduced through sputtering. Since the sputter deposition technique is widely used in device fabrication, attention should be paid to the adverse effects due to the additional defect introduction such as the charge trapping in HEMTs and the non-radiative recombination in LEDs.
Abstract In this study, passivation of thermally-activated recombination centers with hydrogen in n-type float zone (FZ) Si containing nitrogen has been investigated. Prior to hydrogenation samples were heated to 550 °C using rapid thermal annealing and conventional furnaces. A large decrease in minority carrier lifetime occurred upon the heat-treatments confirming previous reports. A sequence of electron traps created in this process have been detected in the deep level transient spectra and characterized. Significant changes in the spectra have occurred after treatments in remote hydrogen plasma and subsequent annealing of the hydrogenated samples in the temperature range 100 °C–400 °C. A total elimination of electrical activity of the thermally induced defects has been observed in the hydrogenated samples subjected to annealing in the temperature range 150 °C–300 °C. The results obtained suggest a simple way for an effective cure of the degraded FZ-Si-based solar cells. Possible defect reactions occurring in the FZ-Si crystals and the role of nitrogen and carbon upon the performed treatments are discussed.
'%3e%3cpath fill='%23012169' d='M0 0v30h60V0z'/%3e%3cpath stroke='%23fff' stroke-width='6' d='m0 0 60 30m0-30L0 30'/%3e%3cpath stroke='%23C8102E' stroke-width='4' d='m0 0 60 30m0-30L0 30' clip-path='url(%23b)'/%3e%3cpath stroke='%23fff' stroke-width='10' d='M30 0v30M0 15h60'/%3e%3cpath stroke='%23C8102E' stroke-width='6' d='M30 0v30M0 15h60'/%3e%3c/g%3e%3c/svg%3e)
'/%3e%3c/g%3e%3cuse xlink:href='%23d' x='45.714'/%3e%3cuse xlink:href='%23e' transform='matrix(-1 0 0 1 479.792 0)'/%3e%3cg id='f' fill='%23fff'%3e%3cpath fill='%23039' d='M232.636 202.406v.005c0 2.212.85 4.227 2.212 5.69 1.365 1.466 3.245 2.377 5.302 2.377 2.067 0 3.944-.905 5.303-2.365 1.358-1.459 2.202-3.472 2.202-5.693v-10.768l-14.992-.013-.028 10.766'/%3e%3ccircle cx='236.074' cy='195.735' r='1.486'/%3e%3ccircle cx='244.392' cy='195.742' r='1.486'/%3e%3ccircle cx='240.225' cy='199.735' r='1.486'/%3e%3ccircle cx='236.074' cy='203.916' r='1.486'/%3e%3ccircle cx='244.383' cy='203.905' r='1.486'/%3e%3c/g%3e%3cuse xlink:href='%23f' y='-26.016'/%3e%3cuse xlink:href='%23f' x='-20.799'/%3e%3cuse xlink:href='%23f' x='20.745'/%3e%3cuse xlink:href='%23f' y='25.784'/%3e%3c/svg%3e)
'/%3e%3c/g%3e%3cuse xlink:href='%23b' transform='matrix(1 0 0 -1 0 549)'/%3e%3c/svg%3e)
