What Do We Know about Hydrogen-Induced Thermal Donors in Silicon?

Abstract

The hydrogen-plasma-accelerated formation of shallow thermal donors in silicon has been studied for a wide range of doping concentration and interstitial oxygen content [normalOnormali] by electrical and spectroscopic techniques. The plasma-hydrogenated material has been heat treated for different times in the temperature range of 275–500°C . It is shown that, besides oxygen thermal donors (OTDs), hydrogen-related shallow thermal donors (STDHs) also play a crucial role in the hydrogen-assisted creation of excess carriers. The impact of different factors on the introduction rate of the shallow donors will be discussed, whereby a strong role is played by the doping concentration and type (i.e., the Fermi-level position during the thermal anneal in air). Generally, shallow donor formation is faster in p- compared to n-type Si, which is associated with the different charge state of H. From combined deep-level transient spectroscopy and Fourier transform infrared absorption spectroscopy, it is concluded that the additional free carriers are contributed by both STDH and OTD centers, so that H not only plays a catalytic role but actively takes part in the donor formation, depending on the experimental conditions. Finally, from our data some conclusions can be made regarding the nature of the STDHs, which is still a matter of debate.

Germanium doping for improved silicon substrates and devices

“…After a 5 h anneal and within the probed substrate depth that corresponds to a maximum applied reverse voltage of 100 V, the carrier concentration increases by a factor of four and a factor of two for the CZ Si and GCZ Si substrates, respectively. This increase of the carrier concentration is due to the generation of oxygen-related thermal double donors [30] as is corroborated by the results shown in Fig. 4, in which the extracted free carrier concentration for the CZ Si and GCZ Si diodes has been plotted as a function of the thermal anneal time.…”

“…This is due to a hydrogen mediated increase of interstitial oxygen diffusivity resulting in a higher TDD formation rate for anneals in a hydrogen containing atmosphere [30].…”

Formation of Submicron n+-Layers in Silicon Implanted with H+-Ions

“…One of the most interesting properties of implanted hydrogen is that its interaction with radiation--induced and native defects during heat treatment leads to the formation of high concentrations (up to 10 17 cm −3 ) of shallow hydrogen-related donors (H-donors) [2][3][4]. It is also important to note that H-donors do not contain oxygen atoms in our case [5]. Most of the donor formation investigations were made for ≈ 100 µm thick floating zone grown Si layers produced using multi-energy H + ion implantation [3,4].…”

Germanium Doping of Si Substrates for Improved Device Characteristics and Yield

“…The results show that the thermal donor (TD) generation rate for GCZ Si (≈ 2.6 × 10 ), in good agreement with previous results obtained on CZ Si substrates with similar oxygen contents (19). Furthermore, there is a faster TD formation in a N 2 /H 2 ambient compared to N 2 due to a hydrogen mediated increase of interstitial oxygen diffusivity (18). Ge doping on electron irradiation hardness.…”

“…After a 5 h anneal and within the probed substrate depth that corresponds to a maximum applied reverse voltage of 100 V, the carrier concentration increases by a factor of four and a factor of two for the CZ Si and GCZ Si substrates, respectively. The increase in the carrier concentration is due to the generation of oxygen-related thermal donors (TD) (18). and is illustrated in the left side of Fig.…”