Barrier Height Enhancement of Al[sub x]Ga[sub 1−x]N∕GaN Schottky Diodes Prepared by P[sub 2]S[sub 5]∕(NH[sub 4])[sub 2]S Treatments

Abstract

The passivation of modulation-doped Al 0.1 Ga 0.9 N/GaN Schottky surfaces by treatment with ͑NH 4 ͒ 2 S and P 2 S 5 /͑NH 4 ͒ 2 S has been investigated. The current-voltage ͑I-V͒ curves of these Schottky diodes demonstrate that the Ti/Pt/Au-Al 0.1 Ga 0.9 N/GaN Schottky diodes prepared by P 2 S 5 /͑NH 4 ͒ 2 S treatment have the lowest reverse-leakage current ͑7.5 nA/cm 2 ͒ and the highest Schottkybarrier height ͑0.98 eV͒. Detailed X-ray photoelectron spectroscopy analysis indicates that a thin sulfide layer on the samples with the ͑NH 4 ͒ 2 S treatment has an improvement for these favorable characteristics. Further, a thin phosphide layer on the samples with the P 2 S 5 /͑NH 4 ͒ 2 S treatment exhibits a larger improvement on the Schottky-barrier height and the reverse-leakage current.The wide-bandgap Al x Ga 1−x N/GaN high-electron mobility transistors ͑HEMTs͒ have great potential for use in high-power and high-frequency microwave power applications 1,2 due to their high temperature, high breakdown, and excellent electron-transport properties. However, reliable Schottky contacts are required before Al x Ga 1−x N/GaN HEMTs can be extensively used. In literatures, many researchers reported effective enhancement of barrier height and reduction of leakage current for Schottky contacts on AlGaN by the insertion of a thin Al layer, 3 the surface control process, 4 and the postannealing process. 5 Additionally, sulfide treatment with the solutions of ͑NH 4 ͒ 2 S 6 and P 2 S 5 /͑NH 4 ͒ 2 S 7,8 is well known to form thin sulfide layers on GaAs-or InP-related semiconductors. Recently, Liu et al. 9 reported that treating Pt/Au Schottky contacts ͑formed on modulation-doped AlGaN/GaN heterostructures͒ with ͑NH 4 ͒ 2 S solution could maximize the Schottky barrier height ͑SBH͒. This proves that ͑NH 4 ͒ 2 S treatment is an effective method in the passivation of Al 0.1 Ga 0.9 N surface. However, the use of P 2 S 5 /͑NH 4 ͒ 2 S to passivate Al 0.1 Ga 0.9 N/GaN Schottky diodes still lacks investigation. Thus, the Al 0.1 Ga 0.9 N/GaN Schottky surfaces prepared by the ͑NH 4 ͒ 2 S and P 2 S 5 /͑NH 4 ͒ 2 S treatment are studied in this work.The Al 0.1 Ga 0.9 N/GaN epi-samples were grown by metallorganic chemical vapor deposition ͑MOCVD͒ on 2 in. sapphire wafers. The structure of the samples comprises a sapphire substrate, a GaN buffer layer, a 2 m undoped GaN layer, and a 0.5 m Si-doped Al 0.1 Ga 0.9 N. The AlGaN/GaN interface is an abrupt from secondary-ion mass spectrometry ͑SIMS͒ analysis. The carrier concentration was 1.29 ϫ 10 17 cm −3 for n-Al 0.1 Ga 0.9 N. All the samples were cleaned by standard processes. The ohmic contacts were initially patterned on the n-Al 0.1 Ga 0.9 N surface using the standard photolithographic lift-off technique. A multilayered Ti/Al/Ti/Au ͑20/100/40/150 nm͒ ohmic contact was deposited on the grown sample by electron-gun evaporation at an applied pressure of 3.2 ϫ 10 −7 Torr. Then, those ohmic contacts were annealed at 900°C for 5 s in ambient N 2 . Three kinds of sulfidation samples were prepared as fo...

Van der Waals Black Phosphorus/Bi10O6S9 Heterojunction Harvesting Ambient Electric Field Energy for Enhanced Photoelectrochemical Sense

“…In Figure f, the 34.98 and 37.12 eV peaks can be attributed to W 4f 7/2 and W 4f 5/2 , respectively. Figure g demonstrates the binding energies of 132.5, 133.22, 133.55, and 134.2 eV corresponding to P 2p 3/2 , P 2p 1/2 , P–S, and P–O bonds, respectively, which are consistent with the P–O–P bond in Figure b. , In Figure h, the 225, 225.7, and 231.86 eV peaks can be attributed to S–S, Bi–S, and S–O bonds, respectively. , …”

GaN-Based High-kPraseodymium Oxide Gate MISFETs withP2S5/(NH4)2SXLin1, Chiu2 2012Active and Passive Electronic ComponentsSelf Cite2000View full textAdd to dashboardCite

“…The information is gathered by "feeling" the surface with a mechanical probe. Piezoelectric elements that facilitate tiny but accurate and precise movements on (electronic) command enable very precise scanning [11]. Figure 5(a) and Figure 5(b) show the 2D and 3D images of the surface roughness on the AlGaN/GaN surface with different treatments, as measured using a Park Systems XE-70.…”

“…Pretreatment before the deposition of the passivating layer between the source, the drain, and the gate terminals is dominated by the effect of surface traps, which cause flicker noise and current collapse problems. For example, (NH 4 ) 2 S X sulfide treatment is known to eliminate native Ga 2 O 3 and As 2 O 3 dangling bonds on GaAs-and InP-related semiconductors, because of the formation of stable Ga-S and As-S bonds during immersion [10,11]. In this work, a P 2 S 5 /(NH 4 ) 2 S X + UV treatment that suppresses surface traps is studied.…”

Electrical Characteristics of AZO/GaN and AZO/ZnO/GaN HBTs With P₂S₅ / (NH₄)₂S Treatments

“…In literatures, many researchers reported sulfur treatment with the solutions of (NH 4 ) 2 S and P 2 S 5 /(NH 4 ) 2 S is well known to form thin sulfide layers on GaAs-or InP-related semiconductors [1], [2]. Additionally, Chang et al reported that treating Schottky contacts formed on AlGaN/GaN heterostructures with P 2 S 5 /(NH 4 ) 2 S solution could maximize the Schottky barrier height (SBH) and have the lowest reverse-leakage current [3]. This proves that P 2 S 5 /(NH 4 ) 2 S treatment is an effective method in the passivation of GaN surface.…”