AlGaN/GaN HEMT grown on large size silicon substrates by MOVPE capped with in-situ deposited Si3N4

et al. 2008

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AlGaN is an important material for ultra‐violet light emitters, photo detectors and high breakdown voltage switching devices. In this work, crack‐free AlxGa1‐xN (5% < x < 55%) layers up to 1.5 μm have been grown on 4 inch Si(111) using an AlN/AlyGa1‐yN (y > 70%) template. The structural quality of AlGaN layers is comparable to that of GaN layers grown on silicon(111). For Al0.16Ga0.84N, the FWHM of HR‐XRD (0002) and (‐1102) ω‐scan is around 650 arc sec and 1200 arc sec respectively. Based on this high quality AlGaN buffer, a double heterostructure (DH) FET was demonstrated. The sheet resistance of DH‐FET is 274 ± 4.7 Ω/□ and the uniformity value of 1.7% is also excellent. Some of the wafers have been processed. Devices with a gate length of 2 μm showed current density of 500 mA/mm and transconductance of more than 200 mS/mm. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

“…After all group IIInitride layer growth was finished, a thin Si 3 N 4 layer was deposited on the AlGaN surface in situ by MOCVD . More growth details can be found in [9][10]16].…”

Section: Methodsmentioning

confidence: 99%

“…In our previous work [9,10], we demonstrated crack-free GaN layers up to 3 µm on 4 inch silicon(111) substrates using step-graded AlGaN intermediate layers. In this study, a similar approach was followed and crack-free Al x Ga 1-x N (5% < x < 55%) layers up to 1.5 µm were achieved on 4 inch silicon(111).…”

mentioning

confidence: 99%

AlGaN‐based heterostructures grown on 4 inch Si(111) by MOVPE

Cheng

Leys

et al. 2008

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“…Today, the sole route towards this goal consists in depositing the GaN active layers onto Si (111) substrates. We have demonstrated elsewhere that it is possible to achieve extremely uniform crack-free and flat AlGaN/GaN HEMT epiwafers on 150 mm Si substrates, paving the way towards GaN on large wafer diameter [3].…”

Section: Introductionmentioning

confidence: 99%

“…Si substrates [3]. Concerning the GaN buffer, careful optimisation of the growth conditions is mandatory.…”

Section: Introductionmentioning

confidence: 99%

In‐situ passivation combined with GaN buffer optimization for extremely low current dispersion and low gate leakage in Si₃N₄/AlGaN/GaN HEMT devices on Si (111)

Germain

Cheng

et al. 2008

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Using Si substrates is the sole route towards III‐nitrides process on large wafer diameter: flat, crack‐free HEMT epiwafers have been grown by MOVPE with diameter up to 150 mm, exhibiting very low sheet resistivity (260 Ω/sq.) and high uniformity (<2%), thanks to in‐situ Si3N4 capping (<5 nm). We show here that simultaneous optimization of GaN growth and of device passivation results in a drastic reduction of buffer and surface traps. This has impact onto device performance, assessed by pulse IV measurements. Drain lag is correlated with the appearance of deep defect‐related peaks in photoluminescence spectra (6 K), and completely eliminated by tuning growth temperature. Gate formation (Ni/Au) onto MOVPE‐grown Si3N4, followed by cleaning and PECVD ex‐situ passivation, leads to very low gate current dispersion, associated to gate leakage current in μA/mm range. Both dc and pulsed characteristics show a current density in the order of 0.8‐1 A/mm, whereas maximal transconductance is 250 mS/mm (Lg = 1 μm). (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

“…2 Results and experiment 2.1 Experiment The AlGaN/GaN HEMT layers were grown on <111> silicon substrates: 22 nm Al 0.3 Ga 0.7 N was grown onto a GaN buffer layer and capped in-situ in the MOCVD reactor with a 3.5 nm silicon nitride layer passivating the surface and protecting it in further processing [7]. The sheet resistance was 261±15 Ω/.…”

mentioning

confidence: 99%

Influence of thermal anneal steps on the current collapse of fluorine treated enhancement mode SiN/AlGaN/GaN HEMTs

Lorenz

Das

et al. 2009

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Gallium nitride based high electron mobility transistors offer high carrier density combined with high electron mobility and enable operation at high frequencies, voltages and temperatures. However, they are generally working in depletion mode, requiring a negative bias to switch them off. As this is disadvantageous for circuit design, power consumption and safety of operation, enhancement mode devices would be favourable. This operation mode can be reached by shifting the threshold voltage towards more positive values by implantation of negatively charged fluorine ions. As these ions were reported to form deep level trap states in the material, we investigated the influence of the implantation and subsequent anneal steps on current collapse and threshold voltage. We found that anneal steps of over 550 °C are effective in reducing the current collapse up to factor 4, but also shift the threshold voltage again to negative values, thus eliminating enhancement mode operation. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)