Dissociation characteristics of proton release in a-SiO2 by first-principles theory

ACS Appl. Electron. Mater.

Zhang

Liu

et al. 2019

Self Cite

The synergistic effects of neutron and gamma ray radiated PNP transistors are systematically investigated as functions of the neutron fluence, gamma ray dose, and dose rate. We find that the damages show a 'tick'-like dependence on the gamma ray dose after the samples are radiated by neutrons. Two negative synergistic effects are derived, both of which have similar magnitudes as the ionization damage (ID) itself. The first one depends linearly on the gamma ray dose, whose slope depends quadratically on the initial displacement damage (DD) and can be attributed to the healing of neutron-radiation-induced defects in silicon. The second one has an exponential decay with the gamma ray dose, whose amplitude shows a rather strong enhanced low-dose-rate sensitivity (ELDRS) effect and can be attributed to the passivation of neutron-induced defects near the silica/silicon interface by the gamma-ray-generated protons in silica, which can penetrate the silica/silicon interface to passivate the neutron-induced defects in silicon. The simulated results based on the proposed model match the experimental data very well, but differ from previous model, which does not assume annihilation or passivation of the displacement defects. The unraveled defect annealing mechanism is important because it implies that displacement damages can be repaired by gamma ray radiation or proton diffusion, which can have important device applications in the space or other extreme environments. Unirradiated Samples Fluence: 0 n/cm 2 Fluence: 2 10 13 n/cm 2 Fluence: 3 10 13 n/cm 2 Fluence: 5 10 13 n/cm 2 LDR: 2.2mrad(Si)/s LDR: 2.2mrad(Si)/s LDR: 2.2mrad(Si)/s LDR: 2.2mrad(Si)/s HDR: 10rad(Si)/s HDR: 10rad(Si)/s HDR: 10rad(Si)/s HDR: 10rad(Si)/s Step 1:Neutron irradiation Step 2:Gamma irradiation FIG. 2. (color online) Flowchart of the neutron/gamma radiation experiments. For each of the eight radiation conditions, 2 chips with 8 PNP transistors are used.

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Acs Applied Electronic Materialsmentioning

confidence: 99%

See 1 more Smart Citation

Mechanism of Synergistic Effects of Neutron- and Gamma-Ray-Radiated PNP Bipolar Transistors

ACS Appl. Electron. Mater.

Zhang

Liu

et al. 2019

Self Cite

“…[33][34][35] Meanwhile, P b centers are converted from E 0 γ centers through an H 2 -mediated two-step process. First, the generated E 0 γ centers interact with pre-existing H 2 and release protons (H þ ) by breaking the H─H bonds [24,[36][37][38][39][40][41]…”

Section: Defect Dynamics Under a Constant Dose Ratementioning

confidence: 99%

Mechanisms and Models for the Suppressed Defect Dynamics in SiO₂–Si Structures under High‐To‐Low Switched Dose Rate Irradiations

Physica Status Solidi (a)

2022

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Ground tests of total ionizing dose (TID) irradiation of silicon (Si) electronic devices are usually carried out under an equivalent constant dose rate, and most theoretical investigations also focused on this ideal situation. However, the practical TID irradiation occurs with variable dose rates. [1] In space missions such as artificial satellites and Mars exploration, the irradiation dose rate changes dramatically as the mission goes on. [2] Especially, for anomalous areas in the South Atlantic (such as the International Space Station) or deep space exploration missions, the dose rate varies within several orders of magnitude, from 10 À5 to 10 rad(Si) s À1 . The time dependence of the concentrations of induced E 0 γ centers and P b centers (also denoted as N ot and N it in the literature) in the dielectric SiO 2 layer and at the SiO 2 /Si interface [3,4] are found to be different for high dose rate (HDR) and low dose rate (LDR) irradiations, especially for bipolar transistors, called as an enhanced low-dose-rate sensitivity (ELDRS) effect. [5] However, at present, it is widely accepted that these different HDR and LDR defect dynamics are relatively independent when they occur in succession. [6] The physical foundation is that HDR and LDR defect dynamics in SiO 2 -Si structures are dominated by different mechanisms, i.e., hole trapping mechanism for LDR and recombination mechanism for HDR, respectively. [7,8] According to this assumption, it has been suggested that the LDR irradiation following HDR irradiation can reproduce the defect dynamics as induced by LDR-only irradiation. [9] In applications, a switched dose rate (SDR) technique [6,10] has been proposed to be equivalent to the LDR-only damage of bipolar devices.However, our recent work [11] demonstrated that HDR and LDR defect dynamics in SiO 2 -Si structures are governed by the same physics: decelerated generation of E 0 γ centers in disordered SiO 2 and reversible conversion between E 0 γ

“…At the same time, the positively charged defects will react with the molecular hydrogen (H 2 ) to generate protons. As the holes are trapped by hydrogenated defects near the interface, protons are likely released . The released protons will migrate toward the a‐SiO 2 /Si interface and react with the passivated dangling bonds, after which the saturated defects are reactivated.…”

Section: Introductionmentioning

confidence: 99%

Computational Study on Interfaces and Interface Defects of Amorphous Silica and Silicon

Physica Rapid Research Ltrs

Zuo

2019

Self Cite

The amorphous SiO2/Si interface is arguably the most important part in semiconductor technology, strongly influencing the device reliability. Its electronic structure is affected by the defects, majorly the dangling bonds known as Pb‐type defects, which have been studied for decades. These defects are usually passivated by hydrogen atoms in device processing, which eliminates the defect levels in the silicon bandgap and thus removes their electric activity. However, when the interface is exposed to ionization radiation, the passivated defects can be reactivated by the protons generated by radiation, which significantly affects the device performance and causes reliability issues. In this review, computational studies on the amorphous SiO2/Si interface and interface defects are summarized, including the modeling of the interface, the main interface defects, and their depassivation, and compared to experimental results. The hyperfine parameters are emphasized, because they are essential to identify the structures of the interface defects. The defect levels and depassivation of the defects are also emphasized, because the former directly affect the device performance and the latter directly generates the dangling bonds in the interface.