Interface dynamics in ohmic contact optimization on AlGaN/GaN heterostructure by the formation of TiN

Meer, Mudassar; Rawat, Akanksha; Takhar, Kuldeep; Ganguly, Swaroop

doi:10.1016/j.mee.2019.111144

Cited by 9 publications

(5 citation statements)

References 24 publications

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“…This finding is consistent with the observations made by Meer et al, who also noted that thicker Al layers result in smaller contact resistance. [4] To further explore the impact of Al thickness in ohmic…”

Section: Resultsmentioning

confidence: 99%

Electrical and X-ray Photoelectron Spectroscopy Studies of Ti/Al/Ti/Au Ohmic Contacts to AlGaN/GaN

OKADA,

FUKINAKA,

AKIRA

2024

IEICE Trans. Electron.

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Section: Resultsmentioning

confidence: 99%

Electrical and X-ray Photoelectron Spectroscopy Studies of Ti/Al/Ti/Au Ohmic Contacts to AlGaN/GaN

OKADA,

FUKINAKA,

AKIRA

2024

IEICE Trans. Electron.

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“…The p-ohmic is formed by depositing the metal stack on top of the SL pair. The SL pair capping is removed by inductivelycoupled-plasma reactive-ion-etching before depositing the n-ohmic metal [14]. The contact resistance for the p-contact is considered to be 4 times that of the n-contact [13] (see supplementary document).…”

Section: Complementary Inverter (Not) Logic Gatementioning

confidence: 99%

“…The SL pairs serve the dual purpose of creating p-channel under negative gate bias and depletes 2DEG at equilibrium. Complementary devices are realized on the same heterostructure using only different ohmic contacts for p-and n-channel transistors [13][14][15] and the same gate metal for both of them [16]. The device characteristics are analyzed through simulations under various conditions.…”

Section: Introductionmentioning

confidence: 99%

GaN-based complementary inverter logic gate using InGaN/GaN superlattice capped enhancement-mode field-effect-transistors

2021

Self Cite

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GaN-based high electron mobility transistors (HEMTs) have received much attention due to their potential usage in radio-frequency and high power applications. However, the development of logic gates has remained mostly elusive due to the still challenging reliable operation of the field-effect enhancement-mode n-transistor and nascent stage for the p-transistor. The n-transistor behavior is mainly achieved by combining the aggressive thinning down of the barrier layer, using charged oxides, and p-doping the cap layer. The p-transistor generally requires a heavily doped p-GaN layer. The realization of both transistors on the same substrate remains challenging due to the conflicting requirements for n- and p-transistors. Here, we propose a GaN-based field-effect complementary transistor device using a p-doped InGaN/GaN superlattice (SL) structure on top of the barrier layer of the HEMT heterostructure. The SL structure changes the electrostatics of the heterostructure by the formation of a two-dimensional hole gas region. An undoped SL structure is shown to be enough to lift the conduction band-edge above the Fermi level to convert the n-transistor from depletion-mode (D-mode) to enhancement-mode (E-mode). The lifting of the bands, in turn, creates a natural quantum-well for the holes in the p-transistor. An additional p-doping of the SL moves the threshold voltage of the E-mode n-transistor further into a positive direction and increases the hole density in the quantum-well E-mode p-transistor. The SL structure, which can be grown by a standard epitaxial process, facilitates the realizations of both the n- and p-transistors. The characteristics of individual devices are further analyzed. A digital inverter gate is simulated, and critical static and dynamic performance parameters are reported. The propagation delay indicates that logic operations can be done at a very high speed compared to those offered by other conventional semiconductors.

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“…[21][22][23] With etching of Ohmic area before metal deposition, contact resistances as low as 0.12 and 0.05 Ω mm have been reported. 25,26 In Au-free Ohmic contacts formed at low temperatures without recess etch, composition and thickness of the AlGaN barrier play a crucial role in determining the contact resistance, which generally increases with an increase in the Al composition of AlGaN and an increase in AlGaN barrier thickness. Other complex methods of selective doping below the contact area have also been proposed.…”

Section: A Effect Of Variation In Etch Chemistrymentioning

confidence: 99%

Au-free recessed Ohmic contacts to AlGaN/GaN high electron mobility transistor: Study of etch chemistry and metal scheme

Niranjan

Guiney²,

Humphreys

et al. 2020

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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The authors study the effect of etch chemistry and metallization scheme on recessed Au-free Ohmic contacts to AlGaN/GaN heterostructures on silicon. The effect of variation in the recess etch chemistry on the uniformity of Ohmic contact resistance has been studied using two different etch chemistries (BCl 3 /O 2 and BCl 3 /Cl 2 ). Experiments to determine the optimum recess etch depth for obtaining a low value of contact resistance have been carried out, and it is shown that near-complete etching of the AlGaN barrier layer before metallization leads to the lowest value of contact resistance. Furthermore, two metal schemes, namely, Ti/Al and Ti/Al/Ti/W, are investigated, and it is found that the Ti/W cap layer on Ti/Al leads to low contact resistance with a smooth contact surface morphology. The effect of maintaining unequal mesa and contact pad widths on the extracted values of contact resistance and sheet resistance using the linear transfer length method (LTLM) has been studied. This is important as LTLM structures are used as monitors for process control during various steps of fabrication. It is shown that the extracted contact resistance and sheet resistance values are reliable when the mesa width is equal to the contact pad width. Finally, a possible mechanism for carrier transport in the Ohmic contacts formed using this process has been discussed, based on temperature dependent electrical characterization, and the field emission mechanism is found to be the dominant mechanism of carrier transport. A low Ohmic contact resistance of 0.56 Ω mm, which is one of the lowest reported values for identical metal schemes, and good contact surface morphology has been obtained with moderate post-metal annealing conditions of 600°C.

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Interface dynamics in ohmic contact optimization on AlGaN/GaN heterostructure by the formation of TiN

Cited by 9 publications

References 24 publications

Electrical and X-ray Photoelectron Spectroscopy Studies of Ti/Al/Ti/Au Ohmic Contacts to AlGaN/GaN

Electrical and X-ray Photoelectron Spectroscopy Studies of Ti/Al/Ti/Au Ohmic Contacts to AlGaN/GaN

GaN-based complementary inverter logic gate using InGaN/GaN superlattice capped enhancement-mode field-effect-transistors

Au-free recessed Ohmic contacts to AlGaN/GaN high electron mobility transistor: Study of etch chemistry and metal scheme

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