• Journal of the Korean Vacuum Society
• /
• v.5 no.1
• /
• pp.6-13
• /
• 1996

The kinetics of native oxide formation on the (Al, Ga)As and (Cd, Mn)Te have been studied by X-ray photoelectron spectroscopy(XPS) and Auger electron spectroscopy(AES). The regrowth of native oxide after 3keV Ar ion sputter etch and deionized water etch has been studied. The previous report exhibited that the native oxide on CdTe and GaAs can be removed completely by deionzied(DI) water only[1]. On the other hand, the airgrown native oxide on (Al, Ga)As become nonhomogeneous and the regrown native oxide on (Cd,Mn)Te can be partially removed.

• Transactions on Electrical and Electronic Materials
• /
• v.14 no.1
• /
• pp.32-35
• /
• 2013

In this paper, a manufacturing process was developed for fabricating high-quality AlGaN/GaN high electron mobility transistors (HEMTs) on silicon carbide (SiC) substrates. Various conditions and processing methods regarding the ohmic contact and pre-metal-deposition $BCl_3$ etching processes were evaluated in terms of the device performance. In order to obtain a good ohmic contact performance, we tested a Ti/Al/Ta/Au ohmic contact metallization scheme under different rapid thermal annealing (RTA) temperature and time. A $BCl_3$-based reactive-ion etching (RIE) method was performed before the ohmic metallization, since this approach was shown to produce a better ohmic contact compared to the as-fabricated HEMTs. A HEMT with a 0.5 ${\mu}m$ gate length was fabricated using this novel manufacturing process, which exhibits a maximum drain current density of 720 mA/mm and a peak transconductance of 235 mS/mm. The X-band output power density was 6.4 W/mm with a 53% power added efficiency (PAE).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.18 no.12
• /
• pp.1101-1105
• /
• 2005

We have investigated the optical properties of Erbium (Er)-implanted GaN by photoluminescence (PL). Various doses of Er ion were implanted on GaN epilayers by ion implantation. Visible green emission lines due to inner 4f shell transitions for $Er^{3+}$ were observed from the PL spectrum of Er-implanted GaN. The emission spectrum consists of two narrow green lines at 537 and 558 nm. The green emission lines are identified as $Er^{3+}$ transitions from the $^{5}H_{11/2}$ and $^{4}S_{3/2}$ levels to the $^{4}I_{15/2}$ ground state. The stronger peaks in the case with the dose of $5{\times}10^{14}cm^{-2}$, together with the relatively higher intensity of the $Er^{3+}$ luminescence in the lower doped sample. It implies that some damage remains in the case with the dose of $1{\times}10^{16}cm^{-2}$. The peak positions of emission lines due to inner 4f shell transitions for $Er^{3+}$ do not change with increasing temperature. It indicates that $Er^{3+}$ related emission depends very little on the ambient temperature.

• Proceedings of the IEEK Conference
• /
• 2001.06b
• /
• pp.25-28
• /
• 2001

In this paper, we have investigated the effects of gas flow rate, rf power, process pressure and Ar addition on reactive ion etching of InP, InGaAs and InAlAs using Sic14 and Cl$_2$ gases. The etch rates were measured by using a surface profiler. The etched profiles, sidewall roughness, and surface morphology were observed by scanning electron microscopy and by atomic force microscopy. The selective etching of InGaAs to InP and InAlAs was studied by varying the etching parameters. It was found that Cl$_2$ gas is more efficient for the selective etching of InGaAs to InAlAs than SiCl$_4$ gas. The etch selectivity of InGaAs to InAlAs is strongly dependent on the rf power and the process pressure.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.20 no.5
• /
• pp.50-55
• /
• 1983

A comprehensive study of the electrical properties of low-dose Si implants in Cr-doped GaAs substrates has been made using the Hall-effect/sheet-resistivity measurement technique for various ion doses and annealing temperatures. The samples were implanted at room temperature and annealed with silicon nitride encapsulants in a hydrogen atmosphere for 15 minutes. H-type layers were produced at all dose levels investigated, and the optimum annealing temperature was 850$^{\circ}C$ for all doses. The highest electrical activation efficiency was 89% for Cr-doped GaAs substrates. Depth profiles of carrier concentrations and mo-bilities are highly dependent upon ion dose and annealing temperature. Significant im-plantation damage still remains after an 800$^{\circ}C$ anneal, and a 900$^{\circ}C$ anneal produces signi-ficant outdiffusion as well as indiffusion of the implanted Si ions.

• Journal of Magnetics
• /
• v.11 no.1
• /
• pp.16-19
• /
• 2006

$2-\mu{m}$ thick GaN epilayer was prepared, and 80 KeV $Co^{-}$ ions with a dose of $3X10^{16}\;cm^{-2}$ were implanted into GaN at $350^{\circ}C$. The implanted samples were post annealed at $700^{\circ}C$. We have investigated the magnetic and structural properties of Co ion-implanted GaN by various measurements. HRXRD results did not show any peaks associated with second phase formation and only the diffraction from the GaN layer and substrate structure were observed. SIMS profiles of Co implanted into GaN before and after annealing at $700^{\circ}C$ have shown a projected range of $\sim390\AA$ with 7.4% concentration and that there is little movement in Co. AFM measurement shows the form of surface craters for $700^{\circ}C$-annealed samples. The magnetization curve and temperature dependence of magnetization taken in zero-field-cooling (ZFC) and field-cooling (FC) conditions showed the features of superparamagnetic system in film. XPS measurement showed the metallic Co 2p core levels spectra for $700^{\circ}C$-annealed samples. From this, it could be explained that magnetic property of our films originated from Co magnetic clusters.

• ETRI Journal
• /
• v.11 no.4
• /
• pp.75-83
• /
• 1989

The diffusion mechanism of Si in GaAs was investigated using different diffusion sources based on the Si-Ga-As ternary phase equilibria. The Si profiles are measured with secondary ion mass spectrometry and differ significantly for sources taken from the different phase fields in the ternary phase diagram. Neutral As vacancy diffusion is proposed for acceptor Si diffusion anneals using a Ga - Si - GaAs source. Donor Si diffusion using As - rich sources and a Si -GaAs tie line source shows concentration dependent diffusion behavior. Concentration dependent diffusion coefficients of donor Si for As - rich source diffusion were found to be related to net ionized donor concentration and showed three regimes of different behavior: saturation regime, intermediate regime,and intrinsic regime. Ga vacancies are proposed to be responsible for donor Si diffusionin GaAs: $Si_Ga^+V_Ga^-$ (donor Si -acceptor Gavacancy) complex for the extrinsic regime and neutral $V_G$a, for the intrinsic regime.The Si - GaAs tie line source resulted in two branch profiles, intermediate between the As - rich and the Ga - rich source diffusion cases.

• Journal of Magnetics
• /
• v.19 no.2
• /
• pp.116-120
• /
• 2014

The spin-lattice relaxation time, $T_1$, for $^{69}Ga$, $^{71}Ga$, and $^{75}As$ nuclei in GaAs:$Mn^{2+}$ single crystals was measured as a function of temperature. The values of $T_1$ for $^{69}Ga$, $^{71}Ga$, and $^{75}As$ nuclei were found to decrease with increasing temperature. The $T_1$ values in GaAs:$Mn^{2+}$ crystal are similar to those in pure GaAs crystal. The calculated activation energies for the $^{69}Ga$, $^{71}Ga$, and $^{75}As$ nuclei are 4.34, 4.07, and 3.99 kJ/mol. It turns out that the paramagnetic impurity effect of $Mn^{2+}$ ion doped in GaAs single crystal was not strong on the spin-lattice relaxation time.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2010.05a
• /
• pp.511-512
• /
• 2010

• Proceedings of the Korean Vacuum Society Conference
• /
• 1994.06a
• /
• pp.133-133
• /
• 1994