Buffer optimization for crack-free GaN epitaxial layers grown on Si(1 1 1) substrate by MOCVD

Arslan, Engin; Öztürk, Mustafa Kemal; Teke, Ali; Özçelik, Süleyman; Özbay, Ekmel

doi:10.1088/0022-3727/41/15/155317

Cited by 111 publications

(114 citation statements)

References 46 publications

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“…3 There are three main types of dislocations that are present in the GaN epitaxial layers. 16,17 The pure edge dislocation with Burgers vector b = 1 3 ͗1120͘ ͑͗a͒͘, the pure screw dislocation with Burgers vec- tor b = ͗0001͘ ͑͗c͒͘, and the mixed dislocation with b = 1 3 ͗1123͘ ͑͗c + a͒͘. These DDs of GaN can be determined from the following equations: 16…”

Section: Resultsmentioning

confidence: 99%

Dislocation-governed current-transport mechanism in (Ni/Au)–AlGaN/AlN/GaN heterostructures

Arslan

Altındal

Özçelik

et al. 2009

Journal of Applied Physics

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The current-transport mechanisms in ͑Ni/ Au͒ -Al 0,22 Ga 0,78 N / AlN/ GaN heterostructures were studied by using temperature dependent forward-bias current-voltage ͑I-V͒ characteristics in the temperature range of 80-410 K. In order to determine the current mechanisms for ͑Ni/ Au͒ -Al 0,22 Ga 0,78 N / AlN/ GaN heterostructures, we fitted the experimental I-V data to the analytical expressions given for the current-transport mechanisms in a wide range of applied biases and at different temperatures. The contributions of thermionic-emission, generation-recombination, tunneling, leakage currents that are caused by inhomogeneities, and defects at the metal-semiconductor interface current mechanisms were all taken into account. The best fitting results were obtained for the tunneling current mechanism. On the other hand, we did not observe sufficient agreement between the experimental data and the other current mechanisms. The temperature dependencies of the tunneling saturation current ͑I t ͒ and tunneling parameters ͑E 0 ͒ were obtained from fitting results. We observed a weak temperature dependence of the saturation current and the absence of the temperature dependence of the tunneling parameters in this temperature range. The results indicate that in the temperature range of 80-410 K, the mechanism of charge transport in the ͑Ni/ Au͒ −Al 0.22 Ga 0.78 N / AlN/ GaN heterostructure is performed by tunneling among those dislocations intersecting the space charge region. The dislocation density ͑D͒ that was calculated from the I-V characteristics, according to a model of tunneling along the dislocation line, gives the value of 0.24ϫ 10 7 cm −2 . This value is close in magnitude to the dislocation density that was obtained from the x-ray diffraction measurements.

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Section: Resultsmentioning

confidence: 99%

Dislocation-governed current-transport mechanism in (Ni/Au)–AlGaN/AlN/GaN heterostructures

Arslan

Altındal

Özçelik

et al. 2009

Journal of Applied Physics

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“…1͒. From the XRD measurements we also estimated the edge and screw type of the dislocation densities, which are used in the mobility cal- 21 for the details of the calculation method of the dislocation density using XRD. The Hall measurements were performed by loading the samples into a closed-cycle He cryostat, in which the temperature varied between 30 and 300 K. Figure 2 shows the 2DEG sheet density and sheet resistance for both samples.…”

Section: Resultsmentioning

confidence: 99%

Comparison of the transport properties of high quality AlGaN/AlN/GaN and AlInN/AlN/GaN two-dimensional electron gas heterostructures

Tülek

Ilgaz

Gökden

et al. 2009

Journal of Applied Physics

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The transport properties of high mobility AlGaN/AlN/GaN and high sheet electron density AlInN/ AlN/GaN two-dimensional electron gas ͑2DEG͒ heterostructures were studied. The samples were grown by metal-organic chemical vapor deposition on c-plane sapphire substrates. The room temperature electron mobility was measured as 1700 cm 2 / V s along with 8.44ϫ 10 12 cm −2 electron density, which resulted in a two-dimensional sheet resistance of 435 ⍀ / ᮀ for the Al 0.2 Ga 0.8 N / AlN/ GaN heterostructure. The sample designed with an Al 0.88 In 0.12 N barrier exhibited very high sheet electron density of 4.23ϫ 10 13 cm −2 with a corresponding electron mobility of 812 cm 2 / V s at room temperature. A record two-dimensional sheet resistance of 182 ⍀ / ᮀ was obtained in the respective sample. In order to understand the observed transport properties, various scattering mechanisms such as acoustic and optical phonons, interface roughness, and alloy disordering were included in the theoretical model that was applied to the temperature dependent mobility data. It was found that the interface roughness scattering in turn reduces the room temperature mobility of the Al 0.88 In 0.12 N / AlN/ GaN heterostructure. The observed high 2DEG density was attributed to the larger polarization fields that exist in the sample with an Al 0.88 In 0.12 N barrier layer. From these analyses, it can be argued that the AlInN/AlN/GaN high electron mobility transistors ͑HEMTs͒, after further optimization of the growth and design parameters, could show better transistor performance compared to AlGaN/AlN/GaN based HEMTs.

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“…The details of the calculation method of the dislocation density use can be found in Ref. [21]. The edge and screw type of the dislocation densities calculated for SC and DC heterostructures are given in Table 1.…”

Section: Resultsmentioning

confidence: 99%

The effect of GaN thickness inserted between two AlN layers on the transport properties of a lattice matched AlInN/AlN/GaN/AlN/GaN double channel heterostructure

et al. 2014

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One AlInN/AlN/GaN single channel heterostructure sample and four AlInN/AlN/GaN/AlN/GaN double channel heterostructure samples with different values of the second GaN layer were studied. The interface profiles, crystalline qualities, surface morphologies, and dislocation densities of the samples were investigated using high resolution transmission electron microscopy, atomic force microscopy, and high-resolution X-ray diffraction. Some of the data provided by these measurements were used as input parameters in the calculation of the scattering mechanisms that govern the transport properties of the studied samples. Experimental transport data were obtained using temperature dependent Hall effect measurements (10-300 K) at low (0.5 T) and high (8 T) magnetic fields to exclude the bulk transport from the two-dimensional one. The effect of the thickness of the second GaN layer inserted between two AlN barrier layers on mobility and carrier concentrations was analyzed and the dominant scattering mechanisms in the low and high temperature regimes were determined. It was found that Hall mobility increases as the thickness of GaN increases until 5 nm at a low temperature where interface roughness scattering is observed as one of the dominant scattering mechanisms. When GaN thicknesses exceed 5 nm, Hall mobility tends to decrease again due to the population of the second channel in which the interface becomes worse compared to the other one. From these analyses, 5 nm GaN layer thicknesses were found to be the optimum thicknesses required for high electron mobility.

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Buffer optimization for crack-free GaN epitaxial layers grown on Si(1 1 1) substrate by MOCVD

Cited by 111 publications

References 46 publications

Dislocation-governed current-transport mechanism in (Ni/Au)–AlGaN/AlN/GaN heterostructures

Dislocation-governed current-transport mechanism in (Ni/Au)–AlGaN/AlN/GaN heterostructures

Comparison of the transport properties of high quality AlGaN/AlN/GaN and AlInN/AlN/GaN two-dimensional electron gas heterostructures

The effect of GaN thickness inserted between two AlN layers on the transport properties of a lattice matched AlInN/AlN/GaN/AlN/GaN double channel heterostructure

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