Electronic Properties and Structure of Boron–Hydrogen Complexes in Crystalline Silicon

Abstract

The subject of hydrogen–boron interactions in crystalline silicon is revisited with reference to light and elevated temperature‐induced degradation (LeTID) in boron‐doped solar silicon. Ab initio modeling of structure, binding energy, and electronic properties of complexes incorporating a substitutional boron and one or two hydrogen atoms is performed. From the calculations, it is confirmed that a BH pair is electrically inert. It is found that boron can bind two H atoms. The resulting BH2 complex is a donor with a transition level estimated at E c–0.24 eV. Experimentally, the electrically active defects in n‐type Czochralski‐grown Si crystals co‐doped with phosphorus and boron, into which hydrogen is introduced by different methods, are investigated using junction capacitance techniques. In the deep‐level transient spectroscopy (DLTS) spectra of hydrogenated Si:P + B crystals subjected to heat‐treatments at 100 °C under reverse bias, an electron emission signal with an activation energy of ≈0.175 eV is detected. The trap is a donor with electronic properties close to those predicted for boron–dihydrogen. The donor character of BH2 suggests that it can be a very efficient recombination center of minority carriers in B‐doped p‐type Si crystals. A sequence of boron–hydrogen reactions, which can be related to the LeTID effect in Si:B is proposed.

Dynamics of Hydrogen in Silicon at Finite Temperatures from First Principles

“…[45] for a recent review). Based on junction spectroscopy and first-principles calculations, the relocation of hydrogen and the formation of a boron-dihydride complex (BH 2 ) in p-type Si has been proposed as a possible culprit for LeTID [46].…”

“…Based on junction spectroscopy and first-principles calculations, the relocation of hydrogen and the formation of a boron-dihydride complex (BH 2 ) in p-type Si has been proposed as a possible culprit for LeTID. [46] The understanding of LeTID is strongly tied with our knowledge regarding the issues discussed above. They involve processes driven by kinetics and excitations (quenching, illumination, annealing), all of which cannot be understood if we leave vibrational and electronic excitations out of the physical picture.…”

Interactions of Hydrogen Atoms with Acceptor–Dioxygen Complexes in Czochralski‐Grown Silicon

“…Comparing the electron affinity of B s O 2 –H structures with the same quantity for a 512‐atom pristine supercell, we have found that the transition level of B s O 2 –H resides above the conduction band minimum for both A and A′ configurations. Hence, as in the reaction between B and H, [ 25 ] the acceptor level of B s O 2 is removed from the gap as a result of its connection to H. No donor transitions were found either.…”

“…Reactions identified in the table as (1)–(3) were already studied in ref. [25]. They show that the binding energy of a bond‐centered proton (ground state of hydrogen in p‐type Si) to is 0.73 eV.…”

Independent Subsystems of Atomic Hydrogen in Silicon Responsible for Boron Passivation and for Dimer Production

“…Another possibility is a single kind of passivating ions, H + (1), but with a compensation by hydrogen‐related donors H 2 B [ 26 ] —positive species that are formed by trapping H + by HB (and thus composed of B − and two H + ). This version was also tried; it can roughly fit the hole profile in Figure 3b but fails to fit the hydrogen profile in Figure 2a.…”