First AlGaN/GaN MOSFET with photoanodic gate dielectric

Mistele, D.; Rotter, Thomas; Röver, K. S.; Paprotta, S.; Seyboth, M.; Schwegler, V.; Fedler, F.; Klausing, H.; Semchinova, O.; Stemmer, J.; Aderhold, J.; Graul, J.

doi:10.1016/s0921-5107(02)00052-1

Cited by 46 publications

(17 citation statements)

References 15 publications

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“…Gallium nitride (GaN) and related compounds have been studied extensively for applications in short wavelength optical devices and high power/temperature devices such as light emitting diodes (LEDs), laser diodes (LDs), metal oxide semiconductor field effect transistors (MOSFETs) and Schottky rectifiers [1][2][3][4]. The performance of these devices depends on the formation of high quality ohmic and Schottky contacts.…”

Section: Introductionmentioning

confidence: 99%

Structural and electrical properties of Mo/n‐GaN Schottky diodes

Reddy

Ramesh

Choi

2006

Physica Status Solidi (a)

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The electrical and structural properties of molybdenum (Mo) Schottky contact to n-type GaN (4.07 × 10 18 cm -3 ) have been investigated before and after annealing at 600 °C. Measurements show that the Schottky barrier height of the as-deposited sample was 0.81 eV (I -V) and 1.02 eV (C -V), respectively. It is shown that when the sample is annealed at 400 °C the Schottky barrier height slightly decreases to 0.74 eV (I -V) and 0.92 eV (C -V), respectively. However, the barrier height degraded to 0.56 and 0.73 eV when the sample was annealed at 600 °C for 1 min in nitrogen ambient. Based on the Auger electron microscopy and X-ray diffraction results, the formation of nitride phases at the Mo/n-GaN interface could be the reason for degradation of Schottky barrier height upon annealing at 600 °C.

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Section: Introductionmentioning

confidence: 99%

Structural and electrical properties of Mo/n‐GaN Schottky diodes

Reddy

Ramesh

Choi

2006

Physica Status Solidi (a)

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“…The combination of the properties of the 2DEG at the heterojunction and the introduction of a thin insulating layer lead to the realization of MOSHFET devices with good DC and HF properties and very low leakage currents [3]. Our group has experienced that by the introduction of photoelectrochemically (PEC) grown Ga 2 O 3 as well as by the introduction of a SiO 2 layer with different pre-treatments, the DC-performance improves and the maximum drain current I Dmax increases [4,5]. Next, Eastman et al report of a sensitive behavior of a SiN x passivation layer with respect to the output RF power of AlGaN/GaN HFETs [6,7].…”

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confidence: 99%

Influence of Process Technology on DC-Performance of GaN-Based HFETs

Mistele

Rotter

Bougrioua³

et al. 2002

phys. stat. sol. (a)

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This work reports on the influence of the surface and the gate length on the performance of AlGaN/GaN based Hetero Field Effect Transistors (HFETs). Differently NH4Sx treated surfaces result in variation of the drain current IDmax of more then 100%. Gate recessing by photoelectrochemical treatment changes the threshold voltage Vth but affects the drain current little. Next, the reduction of the gate length increases the IDmax further by more than 60%. The IDmax values for the transistors are 350 mA mm—1 for the NH4Sx‐treated, 850 mA for the untreated, and 1.43 A mm—1 for the one with a 0.2 μm gate length. The corresponding transconductances gm are 66, 150, and 280 mS mm—1, respectively. Surface analysis with Auger Electron Spectroscopy (AES) and contact characterization (TLM) reveals, that the NH4Sx treatment removes the native oxide and increases the contact resistance as well. Therefore we attribute the increase of IDmax and gm mainly to a beneficial behavior of gallium‐oxide at the surface on the sheet carrier density nS of the 2DEG at the heterointerface.

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“…24,25 The native oxide on an AlGaN alloy has been shown to be a mixture of Ga 2 O 3 and Al 2 O 3 , 26 but the oxide is rich in Al 2 O 3 even at small Al fractions within the semiconductor. 27,28 Prior to metallization, the AlGaN surface was treated at room temperature for 10 min in a solution of either HCl (37%) diluted 1:1 with DI water or buffered oxide etch (BOE). Following the surface treatment, the samples were rinsed in DI water and blown dry with N 2 .…”

Section: Methodsmentioning

confidence: 99%

Environmental sensitivity of Au diodes on n-AlGaN

Readinger

Mohney

2005

Journal of Elec Materi

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With growing interest in AlGaN for ultraviolet detectors and high-power/hightemperature electronic devices, the problem of forming high-quality Schottky contacts to this semiconductor has become increasingly important. It was shown that wet-chemical surface pretreatments affect the as-deposited diode characteristics for Au/n-AlGaN Schottky diodes. However, these diodes improve over the course of days when exposed to air at room temperature, exhibiting reduced leakage currents, enhanced barrier heights, and reduced ideality factors. Exposure to oxygen, with an enhanced effect in the presence of water vapor, is responsible for the environmental aging. The environmental aging was found to occur regardless of the source of AlGaN, surface preparation, and metal deposition technique. It was determined that high asdeposited reverse currents were due to current transport beneath the contact area, rather than across the semiconductor surface. Two findings further suggested that the change in electrical characteristics was due to a phenomenon occurring at the metal/semiconductor interface. First, metal thickness played a key role in the rate of change of the electrical characteristics, with thicker contacts being more impervious to surrounding gas species at room temperature. Second, a metal that readily forms an oxide, Ni, exhibited little environmental aging, while noble metals, such as Au and Pt, showed dramatic effects. Mild anneals revealed that the environmental change was partially reversible, which suggests the passivation of electrically active defects at the metal/semiconductor interface as the cause of the altered diode behavior. Taken together, the data indicate that oxidizing species diffuse through noble metal contacts to the metal/semiconductor interface and passivate electrically active defects, which may be reactivated upon mild anneals in N 2 .

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First AlGaN/GaN MOSFET with photoanodic gate dielectric

Cited by 46 publications

References 15 publications

Structural and electrical properties of Mo/n‐GaN Schottky diodes

Structural and electrical properties of Mo/n‐GaN Schottky diodes

Influence of Process Technology on DC-Performance of GaN-Based HFETs

Environmental sensitivity of Au diodes on n-AlGaN

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