This paper reports the impact of the Mn incorporation on the structural and magnetic properties of Ga1−xMnxN on the metal-organic vapor phase deposition (MOCVD). Crystalline quality and phase purity were determined by high-resolution X-ray diffraction and indicated that no macroscopic second phases are formed during growth. Atomic force microscopy revealed a 2-dimensional MOCVD step-flow growth pattern in the Mn-incorporated samples. Various annealing steps were applied to some of the samples to reduce compensating defects and to investigate the effects of post processing on the growth. SQUID measurements showed an apparent ferromagnetic hysteresis behavior. However, none of the requirements for room temperature ferromagnetism in the prevailing mean field DMS theories were found. Therefore, different origins of the ferromagnetic signal are discussed.

This work initiates an investigation of molecular co-doping to produce p-type centers in (Ga,Al)N with ionization energies lower than Mg. Dopant complexes can be formed between a doubly ionized acceptor such as (Cu, Li or Ag) and a singly ionized donor (silicon). Ion implantation of Cu, Li and Ag into silicon doped GaN films grown by Metalorganic Chemical Vapor Deposition (MOCVD) has been performed. Secondary ion mass spectroscopy (SIMS) data confirmed the simulated depth profile. High resolution X-ray diffraction and Raman spectroscopy were used to characterize the crystalline damage and subsequent recovery upon anneal. A complete recovery was observed after high temperature (700–900°C) annealing. Low temperature (6K) photoluminescence (PL) for Cu-implanted GaN showed bands identified with crystalline lattice damage due to the Cu-implantation. The annealed samples showed recovery of standard crystalline GaN features. Additional donor-acceptor pair features are observed below 3.35 eV indicating the existence of an acceptor state.

The incorporation of chlorine has a significant effect on the dark conductivity of doped and undoped hydrogenated amorphous silicon (a-Si:H). The dark conductivity of a-Si:H films deposited from dichlorosilane (SiCl2H2) and SiH4, and doped with diborane, increases by as much as a factor of 100 over the usual a-Si:H,B films deposited without SiCl2H2. The effect is observed at gas phase concentrations of diborane ranging from 0.006% to 0.5%, and for both DC and RF plasma depositions, although it is more noticeable for the DC discharge. An increase in dark conductivity is also observed in B doped a-Si,C:H films deposited with dichlorosilane, albeit coupled with a change in the Tauc gap. Chlorine reduces the conductivity of undoped and phosphorus doped a-Si:H films. Undoped a-Si:H films deposited from SiCl2H2 and SiH4 have a dark conductivity of ~1. 10-12 S.cm-1, which is an order of magnitude lower than films deposited from pure SiH4. We discuss several alternatives for the mechanism of chlorine enhanced or reduced dopant activation. We have made solar cells using chlorinated p-type a-SiC:H films as the p-layers.

The following lines give a summary of the work concerning Kapteyn’s Plan of Selected Areas up to December 1937.

Two-thirds of the members of the Commission have replied to the request of the chairman for an expression of their opinion. Most of them are in general well satisfied with the existing system of classification and nomenclature. Lindblad reports on successful work upon the determination of absolute magnitudes of faint stars, in many ways. Adams writes: “I might suggest that attention be called in the report to the fact that the ultra-violet spectra, even of stars like β Orionis, show large numbers of lines. As you probably remember, the spectrum of Sirius resembles, at first sight, the solar spectrum. If all observatories had the facilities for getting spectra in the far ultra-violet, this region would probably furnish the best criteria for spectral type.” Merrill suggests: “The nomenclature which, upon the basis of atomic transition, assigns the adjective ‘nebular’ to lines which may not occur in nebulae, and ‘ auroral ‘ to lines which may not occur in the aurora, is surely not an ideal one.

There has been a marked change in the past few years in the incidence of interest in stellar spectra. The great initial task of classification has attained its first objective—though the Henry Draper Extension, and other investigations are still progressing. Perhaps a million stars are still accessible to classification with existing instruments; but more and more time is being spent upon individual spectra, and upon theoretical investigations. In these fields progress has been very rapid, and only some of the more important results may be mentioned here.

Investigation of stellar spectra has been active during the last four years. Without attempting to make a complete survey, some important researches may be mentioned.

The theory of the intensities and contours of absorption lines has been discussed by Eddington, Milne, Pannekoek, Woolley, H. H. Plaskett, and others, and has proved to be difficult. For example, no quantitative theory has yet been developed for the residuai intensity which remains in even the strongest lines, although the physical causes underlying the formation of residual intensities are rather obvious. Study of solar lines with light which has left the surface at different angles shows that the processes which produce the wings and the centre are probably different. The most promising line of attack on this intricate problem appears to be in studies of the solar spectrum, where different regions of the disc may be separately investigated, rather than of integrated starlight. The highest dispersion available, even in solar work, will be none too great.