Transmission Electron Microscopy of Fast-Neutron-Irradiated Silicon

The observation of damage regions produced by neutron irradiation in lithium-doped silicon solar cells

“…Hemment and Gunnersen [13 ] have attempted to observe defect clusters directly by transmission electron microscopy in n-type silicon which was irradiated to a dose of 1019 nvt fast neutrons at a temperature of 60~ but they were unsuccessful. More recently, however, Pankratz et al [14] have observed defects in silicon irradiated at doses between 6 x 1017 and 5 x 19 art fast neutrons at a temperature of 125~ Their material was of a lower purity than that of Hemment and Gunnersen having a resistivity of 300 ~2 cm as compared to 1300 D cm.…”

“…Fujita and Gonser [11] attempted to determine the size of the damage regions in irradiated germanium using an X-ray diffraction technique but were unsuccessful. More recently, there have been several attempts [12][13][14] to observe the damage regions in irradiated germaniums and silicon using the technique of transmission electron microscopy, however, an alternative and perhaps more successful method has been perfected by Bertolotti and co-workers [15][16][17][18]. This consists of irradiating a sample with fast neutrons, etching the surface with suitable chemicals and then obtaiaing a replica for observation in the electron microscope.…”

Recent applications of semiconductor techniques in the study of nuclear radiations

“…The interpretation gains support from the similarity of the annealing curves with those on length changes in deuteron-irradiated germanium (Vook andBaluffi 1959, Vook 1962). It would seem, therefore, the results indicate that there is a difference between silicon and germanium in the formation or importance of large defect clusters resulting from neutron bombardment (Hemment andGunnersen 1966, Stevens 1966). Such a difference may partly arise from the differing vacancy mobilities referred to by , so that in silicon the disordered regions quickly become more spread out and diffuse, or may partly arise from the differing 2 ' s and mean free paths, which would also cause silicon neutron clusters to be more spread out and to contain smaller defect concentrations.…”

“…In semiconductors, these regions are more or less depleted of free carriers and are sometimes termed 'voids'. They can be seen by transmission electron microscopy (Parsons et al 1962, Bertolotti et al 1963, Hemment and Gunnersen 1966, and may contribute to appreciable length changes in the irradiated sample (Vook and Baluffi 1959, Vook 1962, North and Buschert 1964, Stevens 1966. Their effect on electrical parameters and the perturbation of collecting field € may extend well beyond (e.g.…”

Positron annihilation study of silicon irradiated by different neutron doses

“…Dislocations could form in large-dose fast-neutron radiation silicon annealed at a high temperature [3], e.g. at 700°C for 10 min [9]. Above 775°C for NTD Si sample 3 and above 700°C for NTD Si sample 2, most rz values are in the range 231-239 ps (see table 1); the corresponding intensity 12 is also rather large.…”