Gamma Radiation Effects on n-MOSFET I–V Performance

I. Introduction and Related Works

II. DC and Small-Signal Models for an n-MOSFET

III. Static and Dynamic Characteristics of an Irradiated n-MOSFET

III-1 Static Parameters

The n-MOSFET under investigation was fabricated using a 1 µm partially depleted SOI technology. The device is implemented within a 600 µm-diameter circular membrane located near an integrated micro-heater used for in-situ thermal annealing. Two auxiliary PIN diodes are placed on the membrane to monitor the temperature during operation. A detailed description of the fabrication process and the annealing procedure is available in Ref. [12]. Electrical characterization was carried out by measuring the drain current as a function of the gate-to-source voltageV_GS​ in both linear and saturation regimes, with the drain-to-source voltage V_DS​ fixed at 50 mV and 3 V, respectively. Measurements were performed before and after gamma irradiation. The gate dielectric of the investigated n-MOSFET consists of a 25 nm-thick thermally grown silicon dioxide (SiO₂​) layer formed by dry thermal oxidation. The quality of this gate oxide, including its defect density and interface trap concentration, plays a critical role in the device response to gamma radiation exposure. Radiation-induced degradation primarily results from charge trapping within the oxide and from interface state generation at the Si–SiO₂​ interface. Consequently, the parameters employed in the proposed modeling approach, such as the effective trapped charge density and equivalent doping variations, are directly related to these gate oxide properties and the fabrication technology.

Gamma irradiation experiments were performed at room temperature using a calibrated Co-60 source with a dose rate of 1.2 krad(Si)/h. The total ionizing dose was increased up to 348 krad(Si). Electrical measurements were conducted on several nominally identical devices in order to assess reproducibility. All devices exhibited consistent trends with limited sample-to-sample dispersion, and the results presented in this work correspond to averaged values representative of the technology. After irradiation, thermal annealing was performed at 120 °C for 30 minutes in ambient atmosphere using the integrated micro-heater.

The threshold voltage V_th was extracted using the conventional subthreshold extrapolation method. The drain current I_DS was plotted on a logarithmic scale as a function of the gate voltage V_GS ​, and a linear fit was performed in the subthreshold region, where the current exhibits an exponential dependence on V_GS​. The threshold voltage was determined from the intersection of the extrapolated linear fit with the reference threshold current. This extraction procedure, illustrated in Figure 2, follows the methodology reported in Applied Physics Letters 48, 133–135 (1986).

The same extracted V_th values are consistently used in the determination Q_ox-eff and N_A^eff in order to avoid any artificial trend inversion and to ensure physical consistency.

Figure 3. a. The threshold-voltage as a function of Figure3 b. Cross-Sectional schematic of n-MOSFET.

Figure 3. a. The threshold-voltage as a function of Figure3 b. Cross-Sectional schematic of n-MOSFET.

The total Ionizing Dose in the linear regime structure showing the oxide layer, trapped oxide charges, and the effective acceptor concentration in the channel region of a n-MOS capacitance

It clearly appears that the threshold-potential${\mathrm{V}}_{\mathrm{t}\mathrm{h}}$shows a decreasing tendency as TID increases. Using a linear fit, the threshold potential V_th(TID) reads in the linear-regime as:

$$\mathbf{V}\mathbf{t}\mathbf{h}\left(\mathbf{T}\mathbf{I}\mathbf{D}\right)\left[\mathrm{V}\right]=1.53-129{\times 10}^{-5}\times \mathbf{T}\mathbf{I}\mathbf{D}+1.30{\times 10}^{-6}\times {\mathbf{T}\mathbf{I}\mathbf{D}}^2\left[\mathrm{r}\mathrm{a}\mathrm{d}\right(\mathrm{S}\mathrm{i}\mathrm{O}2\mathrm{}\left)\right]$$

(14)

As reported in Ref.[12], the threshold voltage shift $∆{\mathrm{V}}_{\mathrm{t}\mathrm{h}}$is expectedto result from a trapping of positive charges inside the oxide layer and at oxide n-channel. Let ${\mathrm{Q}}_{\mathrm{o}\mathrm{x}-\mathrm{e}\mathrm{F}\mathrm{F}}$ be the total density of oxide-and interface-trapped holes per unit area, $∆{\mathrm{V}}_{\mathrm{t}\mathrm{h}}$is related to Q_ox-effusing the model (12):

$${\mathbf{Q}}_{\mathbf{o}\mathbf{x}}=-{\mathbf{C}}_{\mathbf{o}\mathbf{x}}∆{\mathbf{V}}_{\mathbf{t}\mathbf{h}}[\mathrm{C}/\mathrm{c}\mathrm{m}]$$

(15)

Q_ox-eff represents a charge density per unit area and is therefore expressed in C/cm²

With $∆{\mathbf{V}}_{\mathbf{t}\mathbf{h}}={\mathbf{V}}_{\mathbf{t}\mathbf{h}}\left(\mathbf{T}\mathbf{I}\mathbf{D}\right)-{\mathbf{V}}_{\mathbf{t}\mathbf{h}}(\mathbf{T}\mathbf{I}\mathbf{D}=0)$From V_th=V_th(TID), we have deduced the interfacial gate-oxide density Q_ox-eFF versus TID. Obtained results are shown in Figure 4.

As it is found, Q_ox-eff shows an amount with increased gamma radiation dose. In terms of an analytical fitting, its expression is as follows:

$${\mathbf{Q}}_{\mathbf{o}\mathbf{x}-\mathbf{e}\mathbf{F}\mathbf{F}}\left(\mathbf{T}\mathbf{I}\mathbf{D}\right)=-1.46{10}^{-9}+1.86{10}^{-10}\times \mathbf{T}\mathbf{I}\mathbf{D}-2.009{10}^{-13}\times {\mathbf{T}\mathbf{I}\mathbf{D}}^2[\mathrm{C}/\mathrm{c}\mathrm{m}²]$$

(16)

As an illustrative picture, we report in theFigure 3.b the cross section of the MOS capacitance for a n-MOSFET under bias potentials V_GS and V_DS. The inset clearly shows the deposited interfacial holes under the effect of F_GS electric field. On the other hand, radiation hardening technologies reveal that thin gate oxide designs have a large capacitance which leads to a reduced threshold voltage shift. In terms of quantum tunneling, thin gate-oxide transistors favour the recombination of trapped holes with electrons initially located in the channel [22,23]. This can efficiently help MOSFET devices with thin gate-oxide thicknesses to become more hardened against hostile radiating environments. From the inset of Figure 3, it is seen that the n-channel is located between ionized acceptors in Si-substrate and trapped holes. Physically, this implies that free electrons in the conductive channel are jointly subjected to a double electrostatic interaction. In terms of equilibrium charge balance, acceptors can be considered as partially compensated by equivalent donor centers. This leads to define an effective density of the doped acceptors as ${\mathrm{N}}_{\mathrm{A}}^{\mathrm{e}\mathrm{f}\mathrm{f}.}=\mathsf{\alpha }{\mathrm{N}}_{\mathrm{A}}$ where $\mathsf{\alpha }$represents the centesimal percent of compensation. According to this relation, the threshold voltage shift can be expressed as a function of N_A^eff. using the new model:

$$∆{\mathbf{V}}_{\mathbf{T}\mathbf{h}}\left(\mathbf{T}\mathbf{I}\mathbf{D}\right)=\mathbf{K}[-1+\sqrt{{\displaystyle \frac{{\mathbf{N}}_{\mathbf{A}}^{\mathbf{e}\mathbf{F}\mathbf{F}.}}{{\mathbf{N}}_{\mathbf{A}}}}})]$$

(17)

with $\mathbf{K}={\displaystyle \frac{2}{{\mathbf{C}}_{\mathbf{o}\mathbf{x}}}}\sqrt{{\mathsf{\epsilon }}_0{\mathsf{\epsilon }}_{\mathbf{r}}\mathbf{e}{\mathbf{N}}_{\mathbf{A}}{\mathsf{\varphi }}_{\mathbf{F}\mathbf{i}}}$

In establishing this relation, we have assumed that K does not vary significantly with TID. For the parameters N_A, n_i and C_ox, we have taken the corresponding values 1.1710¹⁷cm^-3, 1,510¹⁰ cm^-3and 1.3810^-3 Fm^-2 respectively. From the measurements of V_th versus TID in the linear regime, we have deduced N_A^eff. and results are summarized in Figure 5. As clearly shown, N_A^eff. (cm^-3) exhibits a decreasing trend as the gamma radiation dose increases. Analytically, the effective doping concentration of acceptors is fitted by a quadratic law according to:

$${\mathbf{N}}_{\mathbf{A}}^{\mathbf{e}\mathbf{F}\mathbf{F}.}\left(\mathbf{T}\mathbf{I}\mathbf{D}\right)=1.19-3.99{10}^{-3}\times \mathbf{T}\mathbf{I}\mathbf{D}+5.41{10}^{-6}\times {\mathbf{T}\mathbf{I}\mathbf{D}}^2\mathrm{i}\mathrm{n}{10}^{-17}\mathbf{c}\mathbf{m}-3$$

(18)

So that, the choice of N_A^eff seems to being physically meaningful as Q_ox-eff to analyze the electron transport in an irradiated n-MOSFET. From ${\mathrm{I}}_{\mathrm{D}\mathrm{S}=}{\mathrm{I}}_{\mathrm{D}\mathrm{S}}\left({\mathrm{V}}_{\mathrm{G}\mathrm{S}}\right)$ measurements in the linear regime, we have also extracted the transconductance. The relevant results are depicted in Figure 5.

Two peculiar features were revealed:(i) For a fixe V_GS the transconductance decreases with increased TID, (ii) Under a gamma radiation dose, the transconductance decreases as the gate-to-source voltage increases. On the other hand, the transconductance can be fitted by the TID-dependent expression:

$${\mathbf{g}}_{\mathbf{m}\mathbf{L}\mathbf{R}}\left(\mathbf{T}\mathbf{I}\mathbf{D}\right)={\mathbf{a}}_0+{\mathbf{a}}_1\times \mathbf{T}\mathbf{I}\mathbf{D}+{\mathbf{a}}_2\times {\mathbf{T}\mathbf{I}\mathbf{D}}^2$$

(19)

$${\mathbf{a}}_0\left({\mathbf{V}}_{\mathbf{G}\mathbf{S}}\right)=21.92-4.085\times {\mathbf{V}}_{\mathbf{G}\mathbf{S}}$$

$${\mathbf{a}}_1\left({\mathbf{V}}_{\mathbf{G}\mathbf{S}}\right)=0.0412-0.104\times {\mathbf{V}}_{\mathbf{G}\mathbf{S}}$$

$${\mathbf{a}}_2\left({\mathbf{V}}_{\mathbf{G}\mathbf{S}}\right)=5.88{10}^{-5}+1.79{10}^{-5}\times {\mathbf{V}}_{\mathbf{G}\mathbf{S}}$$

In the saturation regime, however, measurements of the drain current have been carried out as follows. Figure 6 depicts the relevant I_DS versus TID for different applied V_GS ranging from 1V to 3V.

The drain is subjected to a fixed bias voltage V_DS=3V. The plots reveal that:(i) for a V_GS lower than 1.5V which corresponds to the threshold potential, the drain current does not show a significant change as the TID varies, (ii) Beyond this value, I-V at output exhibits, in contrary, an increasing tendency as TID increases. As it is also noted, the increasing of I_DS is more noticeable with increased V_GS. Similarly to I_DS in the linear regime, saturated I-V characteristics are found to be fitted as a function of TID by a polynomial law with V_GS-dependent coefficients.

$$\begin{gathered} {\mathbf{I}}_{\mathbf{D}\mathbf{S},\mathbf{s}\mathbf{a}\mathbf{t}}\left(\mathbf{T}\mathbf{I}\mathbf{D}\right)={\mathbf{a}}_0+{\mathbf{a}}_1\times \mathbf{T}\mathbf{I}\mathbf{D}+{\mathbf{a}}_2\times {\mathbf{T}\mathbf{I}\mathbf{D}}^2+{\mathbf{a}}_3\times {\mathbf{T}\mathbf{I}\mathbf{D}}^3 \\ {\mathbf{a}}_0{(\mathbf{V}}_{\mathbf{G}\mathbf{S}})=87.37-138.59\times {\mathbf{V}}_{\mathbf{G}\mathbf{S}}+52.27\times {{\mathbf{V}}_{\mathbf{G}\mathbf{S}}}^2 \end{gathered}$$

(20)

$${\mathbf{a}}_1\left({\mathbf{V}}_{\mathbf{G}\mathbf{S}}\right)={\mathbf{a}}_1\left(\mathsf{\mu }\mathbf{A}\times {\mathbf{K}\mathbf{r}\mathbf{a}\mathbf{d}}^{-1}\right)=0.114-0.120\times {\mathbf{V}}_{\mathbf{G}\mathbf{S}}+8.25{10}^{-3}\times {{\mathbf{V}}_{\mathbf{G}\mathbf{S}}}^2$$

$${\mathbf{a}}_2\left({\mathbf{V}}_{\mathbf{G}\mathbf{S}}\right)=2.88{10}^{-3}+2.29{10}^{-3}\times {\mathbf{V}}_{\mathbf{G}\mathbf{S}}-1.54{10}^{-4}{{\times \mathbf{V}}_{\mathbf{G}\mathbf{S}}}^2$$

$${\mathbf{a}}_3\left({\mathbf{V}}_{\mathbf{G}\mathbf{S}}\right)=3.48{10}^{-6}-3.46{10}^{-6}\times {\mathbf{V}}_{\mathbf{G}\mathbf{S}}+7.28{10}^{-8}\times {{\mathbf{V}}_{\mathbf{G}\mathbf{S}}}^2$$

An attempt to explain the latter results will be subsequently proposed. The first feature is predictable since the conductive channel is not yet formed below the threshold potential. While the increase in I_DS as observed for V_GS greater than V_th is due presumably to the flow of an excess of free electrons originating from hole-electron pairs created at the vicinity of the channel in Si-substrate, In n-MOSFET transistors exposed to high TIDs, it is worth noting that this dysfunction can lead to a derivation of the operating point. From I-V measurements performed in the saturation regime, we have deduced as well the transconductance versus TID and V_GS, see Figure 7.

As a main observation, the transconductance shows an increasing trend with increased TID. From a polynomial fitting, it was found that the transconductance can be written under the form:

$$\begin{gathered} {\mathbf{g}}_{\mathbf{m}\mathbf{S}\mathbf{R}}\left(\mathbf{T}\mathbf{I}\mathbf{D}\right)={\mathbf{a}}_0\left({\mathbf{V}}_{\mathbf{G}\mathbf{S}}\right)+{\mathbf{a}}_1\left({\mathbf{V}}_{\mathbf{G}\mathbf{S}}\right)\times \mathbf{T}\mathbf{I}\mathbf{D}+{\mathbf{a}}_2\left({\mathbf{V}}_{\mathbf{G}\mathbf{S}}\right)\times {\mathbf{T}\mathbf{I}\mathbf{D}}^2+{\mathbf{a}}_3\left({\mathbf{V}}_{\mathbf{G}\mathbf{S}}\right)\times {\mathbf{T}\mathbf{I}\mathbf{D}}^3 \\ {\mathbf{a}}_0\left({\mathbf{V}}_{\mathbf{G}\mathbf{S}}\right)=-288.2+146.52\times {\mathbf{V}}_{\mathbf{G}\mathbf{S}} \end{gathered}$$

(21)

$${\mathbf{a}}_1\left({\mathbf{V}}_{\mathbf{G}\mathbf{S}}\right)=0.149-0.117\times {\mathbf{V}}_{\mathbf{G}\mathbf{S}}$$

$${\mathbf{a}}_2\left({\mathbf{V}}_{\mathbf{G}\mathbf{S}}\right)=4.32{10}^{-3}-1.13{10}^{-5}\times {\mathbf{V}}_{\mathbf{G}\mathbf{S}}$$

$${\mathbf{a}}_3\left({\mathbf{V}}_{\mathbf{G}\mathbf{S}}\right)=7.98{10}^{-6}+1.99{10}^{-6}\times {\mathbf{V}}_{\mathbf{G}\mathbf{S}}$$

The latter static parameter to being deduced is the conductance. As an experimental support, the drain current I_DS has been measured versus V_DS only for TID=0 Krad and TID=348 Krad. The gate voltage is fixed at V_GS =3V. From the relevant I-V characteristics, we have determined the conductance versus V_{DS. .} Results are shown in Figure 8.

It is thus found that the conductance shows a large amount with respect to that at TID=0 Krad for V_GS inferior to 2 V, which corresponds to V_DS,SAT. In the saturation regime, however, the conductance does not exhibit a significant change under the impact of gamma radiations. Note that, in the absence of experimental data for intermediate TIDs, it has not been possible to achieve a direct fitting. But the TID-dependence of this parameter can be derived from the transconductance by using the relationships

$${\mathbf{g}}_{\mathbf{D}\mathbf{L}\mathbf{R}}\left(\mathbf{T}\mathbf{I}\mathbf{D}\right){=\mathbf{g}}_{\mathbf{m}\mathbf{L}\mathbf{R}}\left(\mathbf{T}\mathbf{I}\mathbf{D}\right)={\displaystyle \frac{{\mathbf{V}}_{\mathbf{G}\mathbf{S}}-{\mathbf{V}}_{\mathbf{t}\mathbf{h}}}{{\mathbf{V}}_{\mathbf{D}\mathbf{S}}}}\mathbf{F}\mathbf{o}\mathbf{r}\mathbf{V}\mathbf{D}\mathbf{S}<\mathbf{V}\mathbf{D}\mathbf{S},\mathbf{S}\mathbf{A}\mathbf{T}$$

(22)

$${\mathbf{g}}_{\mathbf{D}\mathbf{S}\mathbf{R}}\left(\mathbf{T}\mathbf{I}\mathbf{D}\right)={\mathbf{g}}_{\mathbf{m}\mathbf{S}\mathbf{R}}\left(\mathbf{T}\mathbf{I}\mathbf{D}\right){\displaystyle \frac{{\mathbf{g}}_{\mathbf{m}\mathbf{S}\mathbf{R}}^2}{4\mathbf{W}{\mathsf{\mu }}_{\mathbf{n}}{\mathbf{C}}_{\mathbf{o}\mathbf{x}}}}\sqrt{{\displaystyle \frac{{2\mathsf{\epsilon }}_0{\mathsf{\epsilon }}_{\mathbf{r}\mathbf{s}\mathbf{c}}}{\mathbf{e}{\mathbf{N}}_{\mathbf{A}}{\mathbf{V}}_{\mathbf{D}\mathbf{S}}-{\mathbf{V}}_{\mathbf{G}\mathbf{S}}+{\mathbf{V}}_{\mathbf{t}\mathbf{h}}}}}\mathbf{f}\mathbf{o}\mathbf{r}\mathbf{V}\mathbf{D}\mathbf{S}>\mathbf{V}\mathbf{D}\mathbf{S},\mathbf{S}\mathbf{A}\mathbf{T}$$

The threshold-potential V_Th and the transconductance in both regimes g_mLR and g_mSR have been calculated as a function of TID above.

IV. Summary and Conclusions

References

1. Barnaby, H.J.; Schrimpf, R.D.; Sternberg, A.L.; Berthe, V.; Cirba, C.R.; Sci, R.L. Proton radiation response mechanisms in bipolaranalog circuits. IEEE Trans. Nucl. Sci. 2001, vol. 48, pp. 2074. [Google Scholar] [CrossRef]
2. Menichelli, M.; Alpata, B.; Batliston, R.; Bizzarri, M.; Blasko, S.; Massoa, L.; Fioria, E.M.; Papia, A.; Scalieri, G. Radiation damage of electronic components to beused in a space experiment. NuclearPhysics B 2002, vol. 113, pp. 310. [Google Scholar]
3. Pushppa, N.; Praveen, K.C.; Prakash, A.P.G.; Rao, Y.P.P.; AmbujTripati; Siddaich, D.R. A comparison of 48 MeV Li³⁺ ion, 100 MeV F⁸⁺ ion and Co-60 gamma irradiation effect on N-channel MOSFET. Nucl. Instr. Meth. Res. A 2010, vol. 613, pp. 280. [Google Scholar] [CrossRef]
4. Anjum, A.; Vinayakprasanna, N.H.; Pradeep, T.M.; Pushpa, N.; Krishna, J.B.M.; Prakash, A.P.G. A comparison of 4 MeV Proton and Co-60 gamma irradiation induced degradation in the electricalcharacteristics of N-channel MOSFETs. Nucl. Instr. Meth. Res. B 2016, vol. 379, pp. 265. [Google Scholar] [CrossRef]
5. Freeman, R.; Holmes-Siedle, A. A simple model for predicting radiation effects in MOS devices. IEEE Trans. Nucl. Sci. 1978, vol. 25, pp. 1216. [Google Scholar] [CrossRef]
6. Benedetto, J.M.; Boesch, H.E.; McLean, F.B. Dose and energy dependence of interface trap formation in cobalt-60 and X-ray environments. IEEE Trans. Nucl. Sci. 1988, vol. 35, pp. 1260. [Google Scholar] [CrossRef]
7. Soubra, M.; Cygler, J.; Maskay, G. Evaluation of a dual bias dual metal oxide-siliconsemiconductorfieldeffect transistor detector as radiation dosimeter. Med. Phys. 1994, vol. 21, pp. 567. [Google Scholar] [CrossRef]
8. Schwank, J.R. Radiation Effects in MOS Oxides. In IEEE Trans. Nucl. Sci.; 2008. [Google Scholar]
9. Zebrev, G.I. Physics-based modeling of TID induced global staticleakage. Microelectron. Reliab. 2018. [Google Scholar] [CrossRef]
10. Fleetwood, D.M. Evolution of Total Ionizing Dose Effects in MOS Devices. IEEE Trans. Nucl. Sci., 2018. [Google Scholar]
11. Oldham, T.R.; McLean, F.B. Total ionizing dose effects in MOS oxides and devices. IEEE Trans. Nucl. Sci. 2003, vol. 50, pp. 483. [Google Scholar] [CrossRef]
12. Alvarado, J.; Kilchtska, V.; Boufouss, E.; Soto-Guz; Flandre, D. A compact model for single eventeffects in PD SOI sub-micron MOSFETs. IEEE Trans. Nucl. Sci. 2012, vol. 59, pp. 943. [Google Scholar] [CrossRef]
13. Gwyn, C. Model of radiation-induced charges trapping and annealing in the oxide layer of MOS devices. J. Appl. Phys. 1969, vol. 40, pp. 4886. [Google Scholar] [CrossRef]
14. Pejovic, M.M.; Jaksic, A.B. Contribution of fixed oxide traps to sensitivity of pMOSdosimetersduring gamma ray irradiation and annealing at room and elevatedtemperature. SensorsActuators A: Phys. 2012, vol. 174, pp. 85. [Google Scholar]
15. Amor, S.; André, N.; Kilchytska, V.; Tounsi, F.; Mezghani, B.; Gérard, P.; Ali, Z.; Udrea, F.; Flandre, D.; Francis, L.A. In situ-Thermal Annealing of On-Membrane SOI Semiconductor-BasedDevicesAfter High Gamma Dose Irradiation. Nanotechnology 2017, vol. 28, pp. 184. [Google Scholar] [CrossRef] [PubMed]
16. Amor, S.; Kilchytska, V.; Flandre, D.; Galy, P. The recovery by in situ-annealing in fully-depleted MOSFET with active silicide resistor. IEEE Electron Device Letters 2021, vol. 42, pp. 1085. [Google Scholar] [CrossRef]
17. Laurent, A.F.; Amor, S.; Nicolas, A.; Valeria, K.; Pierre, G.; Zeeshan, A.; Florin, U.; Denis, F. A Lower-Power and In Situ Annealing Technique for the Recovery of Active Device After Proton Irradiation. EPJ Web of Conferences 2018, vol. 170, pp. 01006. [Google Scholar]
18. Schwank, J.R. Radiation Effects in MOS Oxides. IEEE Trans. Nucl. Sci. 2008, vol. 55(no. 4), 1833–1853. [Google Scholar] [CrossRef]
19. Oldham, M.; McLean, F. Total Ionizing Dose Effects in MOS Oxides and Devices. IEEE Trans. Nucl. Sci. 2003, vol. 50(no. 3), 483–499. [Google Scholar] [CrossRef]
20. Lee, L.P. Dose Rate Effects on Radiation-Induced Degradation of MOS Devices. IEEE Trans. Nucl. Sci. 1997, vol. 44(no. 6), 2315–2321. [Google Scholar]
21. Fleetwood, D.M. The Role of Interface States in MOS Device Radiation Response. IEEE Trans. Nucl. Sci. 2013, vol. 60(no. 3), 1706–1720. [Google Scholar] [CrossRef]
22. Saks, N.S.; Ancona, M.G.; Modolo, J.A. Generation of interface states by ionizing radiation in verythin MOS oxides. IEEE Trans. Nucl. Sci. 1986, vol. 33, pp. 1185. [Google Scholar] [CrossRef]
23. Gromov, V.; Annema, A.J.; Kluit, R.; Visschers, J.L.; Timmer, P. A radiation hard bandgapreference circuit in a standard 0.13 µm CMOS technology. IEEE Trans. Nucl. Sci. 2007, vol. 54, pp. 2727. [Google Scholar] [CrossRef]