Interstitial oxygen behavior for thermal double donor formation in germanium: Infrared absorption studies

Abstract

The kinetics of the reduction of interstitial oxygen (Oi) due to the formation of thermal double donors (TDDs) upon heat treatment in an oxygen-rich Ge crystal were investigated at various temperatures. Specimens were prepared from a Ge crystal with oxygen at a concentration of 4–5 × 1017 cm−3 grown by a new Czochralski method and were heat-treated in the temperature range 300–500 °C. Shrinkage of a dissolved oxygen absorption peak at 855 cm−1 and simultaneous development of a thermal double donor peak at 780 cm−1 were observed by infrared absorption spectroscopy at room temperature. The formation of TDDs was also detected electrically. Reduction of dissolved oxygen concentration upon the heat treatments was kinetically analyzed. The activation energy of the reduction of Oi concentration was evaluated to be 1.7 and 2.0 eV in the early and prolonged stages of the heat treatment, respectively, close to that of Oi diffusion. From the results, TDD development process was indicated to be the merge reaction of Oi-Oi to form oxygen dimers (Odimer) in the early stage of the heat treatment and further enlargement of Odimer to TDDs by absorbing Oi in the prolonged stage of the heat treatment in accordance with the On-2NN model.

Effect Of Annealing On The Behavior Of Oxygen Dissolved In Germanium And Optical Properties Of Single Crystals

“…We can suggest considering the findings of the experiments in the studies [10][11][12]17] The phenomenon observed in a similar way in papers [11,16] can be explained by the formation of thermal donors (TD) based on dissolved oxygen in the germanium crystal lattice during annealing. Thus, the part of dispersed oxygen is bound in TD structure due to annealing.…”

“…It is the general practice to determine oxygen concentration in the crystals by the absorption peak at 856 cm −1 in the infrared spectra, which is identified with asymmetrical vibration mode 3 [7][8][9]. In the recent research [10][11][12] the oxygen peak at 856 cm −1 has been reported to have a "shoulder" at , that equals 843 cm −1 , which is also identified with O vibrations.…”

“…It should be noted that oxygen concentration in the crystals investigated in the studies [7][8][9][10][11][12][13][14][15][16] is typically ∼10 17 cm 3 or higher. Thus, germanium was oxygen enriched.…”

“…Dislocations and foreign impurities limit the use of germanium in infrared optics, since they change the optical properties of germanium [5]. Recent studies have proved the oxygen to be one of the main impurities affecting structural perfection, electrical and optical properties of germanium single crystals, and operational characteristics of Ge-based electronics [7][8][9][10][11][12][13][14][15][16][17].…”

Oxygen Impurity in Germanium Single Crystals Determination by Infrared Spectrometry

“…The oxygen concentration in the crystals investigated earlier is typically near 10 17 cm −3 or higher. Thus, germanium was adequately enriched in oxygen [9][10][11][12].…”