Magnesium‐Related Donors in Silicon: State of the Art

Abstract

The research interest in deep donors in silicon is due in particular to the quantum structure of such centers; these are promising for application in silicon photonics in the mid-IR range and quantum technologies. At interstitial lattice positions, magnesium atoms create double-charge deep donors. The review is an attempt to summarize the accumulated knowledge on properties of magnesium impurity in silicon. Among methods to obtain magnesium-doped silicon, there is focus on the impurity diffusion from the solid phase using the so-called sandwich method. Techniques to investigate samples include Hall effect measurements, optical absorption, luminescence spectroscopy, and others. The diffusivity of magnesium in silicon and stability of parameters of doped samples under heat treatment is discussed. The energy spectrum of the helium-like magnesium donor is considered in detail. Due to the interaction with other impurities, magnesium forms a variety of donor levels in silicon. These include complexes of Mg with substitutional acceptor atoms B, Al, Ga, In, interstitial Li, and oxygen, as well as numerous donors with a currently unknown nature. Some defects are similar to so-called thermal donors in silicon. The pairing of Mg atoms is proved in samples prepared from the isotope 28 Si-enriched silicon.

Diffusion of Magnesium in Czochralski Silicon

“…Experiments show that homogeneous doping over a sample area is achieved by depositing a sufficiently high specific mass of magnesium m Mg on the crystal surface. [9] In the present work, the value of m Mg is %500 μg cm À2 . We then covered the magnesium-coated sides of the wafers with 0.4-0.5 mm-thick auxiliary silicon plates, placed a prepared sandwich in a quartz cassette, and fixed it with silicon wedges (see a schematic representation of such a setup in Figure 1).…”

“…Temperature dependences of the magnesium diffusion coefficient in Cz‐grown silicon, present work data, and dislocation‐free Fz‐grown silicon. [ 9 ] The diffusion activation energy E is shown for both cases.…”

“…The magnesium impurity in silicon is mainly electrically inactive, as observed in various sample preparation methods–ion implantation, epitaxial growth of Si:Mg films, and sandwich method. [ 9 ] An interesting problem for further research is whether the accumulation of electrically neutral magnesium impurities in a crystal affects the magnesium diffusion process. Within the framework of the present study, for the Cz silicon, such an influence can be caused by the interaction of neutral magnesium with oxygen, which may change the concentration of oxygen‐related traps.…”

“…[4][5][6] The diffusivity of magnesium in Si is much higher than that of substitutional impurities. [7,8] Magnesium in silicon can form electrically active complexes with other impurities (see review article [9] ). Experimental data indicate that most of the magnesium in Mg-doped silicon is electrically inactive.…”

“…Magnesium in silicon can form electrically active complexes with other impurities (see review article [ 9 ] ). Experimental data indicate that most of the magnesium in Mg‐doped silicon is electrically inactive.…”