Damage-Free Ion Beam Doping of Carbon During Molecular Beam Epitaxy of GaAs

1993 ◽  
Vol 316 ◽  
Author(s):  
Yunosuke Makita ◽  
Tsutomu Iida ◽  
Shinji Kimura ◽  
Stefan Winter ◽  
Akimasa Yamada ◽  
...  

ABSTRACTRecently, we introduced various acceptor impurities into MBE-grown ultra-pure GaAs by conventional high-energy ion implantation and found many novel shallow emissions associated with acceptor-acceptor pairs. Most of these emissions were easily quenched by extremely small amount of residual donor atoms which were unintentionally introduced during doping processes. For the interpretation of impurity effects, the usage of mass-separated atom as dopant source was strongly suggested. Along this consideration, we developed combined ion beam and molecular beam epitaxy (CIBMBE) technology, in which damage-free doping with high mass purity (M/ΔM=100) is expected to be possible. We here present the results of low-energy (100 eV) carbon ion doping using CIBMBE method. Samples were prepared asa function of growth temperature (Tg=400-700°C) and ion beam current. Net hole concentration, |NA-ND| as high as ~1×1020 cm-3 was obtained in as-grown samples. In 2K photoluminescence spectra, emissions due to acceptor-acceptor pairs exhibit specific energy shift with growing |NA-ND|. Results indicate that carbon doping can be made efficiently even at Tg as low as 500°C without any post heat treatment. These results also tell that by CIBMBE method no serious radiation damages are produced and the undesired impurity contamination can be considerably suppressed.

1995 ◽  
Vol 388 ◽  
Author(s):  
Y. Makita ◽  
T. Iida ◽  
T. Shima ◽  
S. Kimura ◽  
A. Obara ◽  
...  

AbstractCarbon ion (C+) irradiation during molecular beam epitaxy (MBE) growth of GaAs/GaAs and in0.53.Ga0.47As/InP layers was carried out using CIBMBE (combined ion beam and molecular beam epitaxy) method as a function of wide acceleration energy (Ea=30 eV-30 keV) at a constant ion beam current density. Judging from the monitored current density and the net hole concentration (INA-ND|) obtained from Hall effect measurements, activation rate as high as 88% was achieved for as-grown GaAs layers by C+ ion irradiation of Ea=~170eV. It was revealed that by annealing at 800°C, a slight enhancement (~ 10%) of INA-ND| is practiced for Ea <~ 130eV but a significant increase of INA-ND| is realized for Ea>~lkeV. IN in0.53Ga0.47As/InP layers with increasing Ea, a type conversion of electric conduction from n to p was found to occur at Ea= ~70~100eV. these observations describe that Ea plays a vital role to determine the location of incorporated electrical and optical active impurities in GaAs and inGaAs. Further for comparison, C+-implanted GaAs layers were prepared by high-energy (400 keV) ion-implantation as a function of substrate temperature (T1=RT-600 °C). For C dose concentration of lxl018cm-3\ the highest activation rate of ~20 % was obtained at T1=~150 °C. This result states that CIBMBE method is a superior doping method in view of activation rate of introduced dopants and the formation of damage-free ion-irradiated layers.


1994 ◽  
Vol 340 ◽  
Author(s):  
C. R. Abernathy ◽  
S. J. Pearton ◽  
P. W. Wisk ◽  
W. S. Hobson ◽  
F. Ren

ABSTRACTA comparison of dimethylethylamine alane (DMEAA) and trimethylamine alane (TMAA) as aluminum sources and CBr4 and CC14 as carbon doping sources for deposition of AlAs by metalorganic molecular beam epitaxy (MOMBE) has been carried out. DMEAA was found to produce the lowest oxygen levels in AlAs, 5 x 1017 cm-3 VS. 1021 cm-3 for TMAA, even at growth temperatures as low as 500°C. This reduction is likely due to the absence of oxygenated solvents used during synthesis of the DMEAA. Undoped films grown from either source were fully depleted as-grown. Through the use of CBr 4, hole concentrations up to 4.5x1019 cm-3 were achieved in AlAs layers grown fiom DMEAA. Attempts to increase the hole concentration beyond this level resulted in a decrease in the hole concentration even though SIMS analysis showed the carbon concentration to increase with increasing dopant flow. Though the carbon sources did not appear to introduce additional oxygen, they appear to introduce other impurities, such as Cl and Br. Also, due to parasitic etching reactions with the adsorbed halogen, the use of these sources reduces the Al incorporation rate.


1993 ◽  
Vol 316 ◽  
Author(s):  
Tsutomu Iida ◽  
Yunosuke Makita ◽  
Stefan Winter ◽  
Shinji Kimura ◽  
Yushin Tsai ◽  
...  

ABSTRACTC-doped GaAs films were prepared by novely a developed, combined ion beam and molecular beam method (CIBMBE) as a function of hyperthermal (30–500 eV) energies (EC+) of carbon ion (C+) beam. Ion beams of a fixed beam current density were impinged during molecular beam epitaxy growth of GaAs at substrate temperature of 550 °C. Low temperature (2 K) photoluminescence (PL) has been used to characterize the samples together with Hall effects measurements at room temperature. Through the spectral evolution of an emission denoted by [g-g]β which is a specific emission relevant to acceptor-acceptor pairs, the activation rate was confirmed to increase with increasing EC+ for EC+ lower than 170 eV. It was explicitly demonstrated that the most effective Ec+ to establish highest activation rate is located at ~170 eV. This growing activation rate was suggested to be attributed to the enhanced migration of both impinged C and host constituent atoms with increasing EC+. This surmise was supported also by Hall effect measurements which revealed the maximum net hole concentration ( |NA-ND| ) for EC+=170 eV. For EC+ higher than ~170 eV, increasing EC+ was found to induce the reduction of activation rate. It was suggested that this observation is ascribed not to the formation of C donors but to the enhanced sputtering effect of impinged C+ ions with increasing EC+.


1988 ◽  
Vol 128 ◽  
Author(s):  
Eric Chason ◽  
K. M. Horn ◽  
J. Y. Tsao ◽  
S. T. Picraux

ABSTRACTUsing in situ, real-time reflection high energy electron diffraction (RHEED), we have measured the evolution of Ge (001) surface morphology during simultaneous molecular beam epitaxy and Ar ion beam bombardment. Surprisingly, low-energy Ar ions during growth tend to smoothen the surface. Bombardment by the ion beam without growth roughens the surface, but the surface can be reversibly smoothened by restoring the growth beam. We have measured the effect of such “ion beam growth smoothening” above and below the critical temperature for intrinsic growth roughening. At all measured growth temperatures the surface initially smoothens, but below the critical roughening temperature the final surface morphology is rough whereas above this temperature the final morphology is smooth.


1995 ◽  
Vol 150 ◽  
pp. 236-240 ◽  
Author(s):  
Tsutomu Iida ◽  
Yunosuke Makita ◽  
Shinji Kimura ◽  
Yoko Kawasumi ◽  
Akimasa Yamada ◽  
...  

1987 ◽  
Vol 94 ◽  
Author(s):  
S. B. Ogale ◽  
M. Thomsen ◽  
A. Madhukar

ABSTRACTComputer simulations of III-V molecular beam epitaxy (MBE) show that surface reconstruction induced modulation of kinetic rates could give rise to ordering in alloys. Results are also presented for the possible influence of an external ion beam in achieving low temperature epitaxy as well as smoother growth front under usual conditions.


2001 ◽  
Vol 30 (6) ◽  
pp. 785-788 ◽  
Author(s):  
B. L. Vanmil ◽  
A. J. Ptak ◽  
N. C. Giles ◽  
T. H. Myers ◽  
P. J. Treado ◽  
...  

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