KR20150125154A - growth control method of Au droplets on GaAs substrate - Google Patents

Abstract

According to an aspect of the present invention, provided is a method for growth control of Au droplets on a GaAs substrate depositing Au droplets on a GaAs substrate by self-formation in a vacuum plasma ion coating chamber by pulsed laser deposition. Any one feature among average height, diameter of side surface, density, and surface roughness of a nanostructure of the deposited Au droplets is controlled by thermal treatment temperature or amount of Au deposition in a deposition process.

Description

[0001] The present invention relates to a growth control method of Au droplets on a GaAs substrate,

The present invention relates to a method of controlling the growth of Au droplets on a GaAs substrate and a method of depositing Au using the method.

Recently, interest in nanoparticles is increasing. For example, as a general nanomaterial with excellent optoelectronic properties, gold particles have been widely used in the sensor field due to their sensitivity range, optimization characteristics and sensitivity enhancement. Moreover, gold particles have many surprising properties through the epitaxial growth mechanism Has attracted attention as a catalyst for catalyzing one-dimensional nanostructures, for example, nanopillars and nanowires.

The nanowire is formed by reacting a metal catalyst material such as Au, Ni, Cu or the like with a raw material on a silicon wafer to form an eutectic alloy, and adding a monosilane the nanowires are produced through the process of precipitation upon supersaturation using mono-silane (SiH 4) or tetrochlorosilane (SiCl 4) as precursors.

In vapor-liquid-solid (VLS) growth, the gaseous atoms can be selectively absorbed by metallic Au droplets in the liquid phase to form catalyst alloy droplets on the substrate. Nucleation and growth of nanowires from supersaturated catalytic alloy droplets can occur at the gas-liquid interface due to the greater surface adsorption probability at the interface. The control of the density, length and diameter and growth rate of such nanowires can be varied by the density, length and diameter of the metal Au drops.

In order to produce a desired nanowire for various purposes, control characteristics for the size and density height due to the growth of Au droplets are required.

A conventional technique for manufacturing silicon nano-wire by depositing gold with a catalyst is disclosed in Korean Patent Registration No. 10-1287611.

Korean Registered Patent No. 10-1287611 [Method of producing silicon nanowire]

The present invention provides a control method for size, density and surface roughness of spontaneously-formed Au droplets according to changes in heat treatment conditions and deposition amounts on GaAs.

According to an aspect of the present invention, there is provided an Au deposition method for depositing Au droplets by a spontaneous-formation method under a vacuum plasma ion deposition chamber on a GaAs substrate by a pulse laser deposition method, There is provided a method of controlling Au growth on a GaAs substrate which controls at least one of height, side diameter, density and surface roughness by heat treatment temperature or deposition amount of Au in the deposition process.

The control of the annealing temperature may be performed by controlling the annealing temperature to a target temperature in the range of 100 to 550 ° C. after depositing the Au deposition amount to a predetermined thickness of 2 nm to 20 nm, do.

The control by the heat treatment temperature is performed by using the characteristic that the average height and the side diameter are increased and the density is decreased when the heat treatment temperature is raised.

Further, the diffusion distance l _D related to the side diameter is calculated by the following equation.

,

,

(Where D is the surface diffusion coefficient, T is the residence time of the atom, and T _sb is the annealing temperature Ta)

Further, the density is reduced in proportion to the increase of the diffusion distance l _D.

In addition, in order to form the deposited Au droplets so as to have a dome-like characteristic having uniformity, the heat treatment temperature is controlled in the range of 400 ° C to 550 ° C.

The annealing temperature may be controlled in a range of 250 to 250 ° C so that the surface of the deposited Au droplet has a wavy nanostructured characteristic.

The control by the heat treatment temperature is controlled by the characteristic that the density is reduced in the range of 26.5 to 27.4 x 10 < ⁶ > cm & lt ^{; 2} > .

The control of the deposition amount of Au by the deposition amount of Au is performed by controlling the deposition amount of the Au in the range of 2 to 20 nm and then performing a heat treatment process at a temperature of 823 K under a vacuum of less than 1 x 10 ^-4 Torr in a PLD chamber .

It is to be noted that the surface roughness is controlled by the deposition amount of Au in the range of 2 nm to 9 nm in the case of the deposition amount of Au of 3.086 nm per 1 nm Au deposition (the surface state is a value calculated by the root mean square) And the surface roughness is controlled by the characteristic that the average deposition amount per 1 nm of deposition is decreased to a reduction rate of 0.809 nm (the surface state is a value calculated by the root mean square) in the range of the deposition amount of Au exceeding 9 nm to 20 nm .

The control by the deposition amount of Au is such that circular dome-shaped mini droplets having a density in the range of 1.9 × 10 ⁹ / cm 2 to 4.48 10 ¹⁰ are produced in the range of the Au deposition amount in the range of 2 to 6 nm, In the range of 10 to 20 nm or more, 6.1 10 ⁸ to 1. 12 X 10 < ⁸ > and a large Au droplet having a low density in the range of 10 < ⁸ >

Further, the control of the deposition amount of Au by the Au deposition amount is such that when the deposition amount of Au is changed from 2 nm to 20 nm, the average height of the Au droplets to be formed is increased 4.26 times to the average height of the deposition amount of 2 nm, And the lateral diameter is controlled to be 8.25 times the lateral diameter of the deposition amount of 2 nm.

According to one embodiment of the present invention, the detailed evolution of the spontaneously-formed Au nanostructures, including Au droplets and incorporated Au nanostructures, can be achieved by systematically varying the deposition amount of Au deposited on GaAs, Au control features.

In addition, according to one embodiment of the present invention, a systematic control characteristic on the deposition amount of Au to obtain a desired nano structure of Au droplets on GaAs by changing the heat treatment temperature under a fixed deposition amount is presented .

According to an embodiment of the present invention, the variation element of the pattern according to the variation of the amount of Au deposition described above can be utilized as a growth control method in the manufacturing process according to the deposition of Au by using it as a control factor of Au droplet deposited on GaAs.

According to one embodiment of the present invention, Au droplets having the size, density, and surface roughness characteristics required by controlling the amount of Au deposition under a fixed heat treatment temperature on GaAs can be manufactured.

According to one embodiment of the present invention, the pattern change factor according to the above-described heat treatment change can be utilized as a growth control method in the manufacturing process according to the Au deposition by using the change factor as the control factor of the Au droplet deposited on the GaAs.

According to an embodiment of the present invention, it is possible to fabricate a feature of size and density required by controlling the heat treatment temperature under the deposition amount fixed on GaAs by growing Au droplets.

Figure 1 shows growth patterns of spontaneously-formed Au droplets on GaAs according to the deposition thickness.
FIGS. 2 to 3 show the surface change pattern at a deposition amount of spontaneously formed Au droplets on GaAs (111) B of 2 nm to 4 nm according to an embodiment of the present invention.
FIG. 4 illustrates the size and density of spontaneously formed Au droplets formed on GaAs (111) B for each deposition amount according to an embodiment of the present invention.
Figure 5 shows the variation of spontaneously-formed Au drops on GaAs (111) B according to the deposition amount of 6-20 nm according to an embodiment of the present invention.
Figure 6 shows a SEM image of a large area for each deposition amount.
FIGS. 7-9 show evolution patterns of spontaneously formed Au droplets on GaAs (110) by deposition amount variation according to an embodiment of the present invention.
FIG. 10 is a graph showing changes in spontaneous-formed Au droplets on GaAs (111) A according to an annealing temperature in the manufacturing process according to an embodiment of the present invention.
11 shows the nanostructure of spontaneously formed Au particles on GaAs (111) A induced by a change in the heat treatment temperature (Ta) in the range of 250 < 0 > C to 350 < 0 > C.
Figure 12 shows the evolution pattern of spontaneously formed Au droplets on GaAs (111) A with a heat treatment temperature of 400 ° C to 550 ° C.
FIG. 13 is a graph showing the size and density of spontaneously-formed Au droplets on a GaAs substrate according to a heat treatment temperature of 400 ° C to 550 ° C.
Figure 14 illustrates the evolution of spontaneously formed Au droplets on GaAs (110) contributed by a heat treatment temperature change ranging from 250 ° C to 550 ° C.
Figure 15 shows the evolution of spontaneously formed Au droplets on GaAs (100).
Figure 16 shows the evolution of spontaneously formed Au droplets on GaAs (111) B.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

According to an embodiment of the present invention, there is provided a method of controlling spontaneously-formed Au droplets on the substrates 111 A, 110, 100, and 111 B of GaAs according to changes in heat treatment conditions.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In one embodiment of the present invention, "AH" means an average height of spontaneously formed Au droplets formed on GaAs, and "LD" means an average side diameter of spontaneously formed Au droplets formed on GaAs. "AD" means the average density of spontaneously formed Au droplets formed on GaAs.

In the present invention, the surface roughness (R _q ) means a value calculated by root mean squared (RMS) of the surface state induced by the droplet evolution.

Figure 1 shows the growth of spontaneously-formed Au droplets on GaAs.

1 (a) shows a GaAs (111) B surface before Au deposition, and Fig. 1 (a-1) shows a cross-sectional surface line profile.

1 (b) shows a GaAs (111) B surface after 20 nm Au deposition.

Deposition amounts varied systematically to show an effect in the range of 2 to 20 nm, and the surface showed a very smooth surface morphology after deposition of 20 nm.

Figure 1 (c) shows the spontaneously formed Au droplets generated at a deposition of 3 nm after a systematic heat treatment at 823K.

Figure 1 (d) shows spontaneously formed Au droplets produced with a deposition amount of 12 nm, with a heat treatment of 823 K.

In Fig. 1, the AFM side view of Figs. 1 (a) to 1 (d) is 1 x 1 m.

1 ((a-1) to (d-1) show cross-sectional surface line profiles, respectively.

Referring to FIG. 1, it can be seen that the spontaneously-formed Au droplets under the same growth conditions have a significant difference in size and density depending on the amount of Au deposition.

The fabrication of the spontaneously-formed Au droplet on the GaAs surface according to an embodiment of the present invention applies a pulse laser deposition (PLD) system and proceeds to the next step.

First, the GaAs (111) B and (110) substrates are bonded side by side to the Inconel sample holder due to the good thermal conduction.

Next, the degassing process is carried out in a vacuum chamber at 623 K for 30 minutes at less than 1 x 10 ^-4 Torr (1 Torr = 101 325 Pa).

The Au deposition is performed under a vacuum plasma ion-coating chamber of less than 1 x 10 < ^-1 > Torr with a 3 mA ionization current.

Next, in an embodiment of the present invention, Au of 2, 2.5, 3, 4, 6, 9, 12 and 20 nm are deposited with a deposition rate of 0.05 nm s ^-1 , respectively, to observe the control characteristics thereof.

A systematic heat treatment immediately after the deposition of Au with the thickness described above is performed in a vacuum of less than 1 x 10 < ^-4 > Torr in a PLD chamber.

The manufacturing process is performed by a computer-controlled recipe and the substrate temperature (T _sub ) is gradually raised to a target temperature of 823 K at a rate of 1.356 K s ^-1 by the heat treatment temperature. After reaching the target temperature, the sample is held for 150 seconds to ensure growth of the Au droplet for each growth.

After the heat treatment, the substrate is immediately quenched to an ambient temperature to minimize Ostwald ripening.

In one embodiment of the present invention, sputter-formed Au droplets on GaAs (111) B on the GaAs (111) B substrate are measured for the variation pattern and the effect on the deposition amount in order to find the control characteristic of the Au droplet.

Fig. 2 shows a change pattern when spontaneously-formed Au drops on GaAs (111) B according to an embodiment of the present invention are deposited in an amount of 2 to 4 nm.

2 (a) through 2 (d) are top views of an AFM image of 3 x 3 m, and Figs. 2 (a-1) Top surface.

Figs. 2 (a-2) to (d-2) show an AFM side image of 1 x 1 탆.

Figure 3 shows the cross-sectional line profile of Figure 2;

Figures 3 (a) - (d) are surface cross-sectional line profiles of each sample at points indicated by white lines in the AFM images of Figures 2 (a-1) to (d-1).

FIG. 4 illustrates the size and density of spontaneously formed Au droplets formed on GaAs (111) B for each deposition amount according to an embodiment of the present invention.

4A is an average height (AH) of spontaneously formed Au droplets generated on the GaAs 111 B with respect to each deposition amount, and FIG. 4B is a side diameter LD according to the deposition amount.

4 (c) is the average density (AD) of spontaneously formed Au droplets formed on GaAs (111) B with respect to the deposition amount.

4 (d) shows the surface roughness (R _q ) change with respect to the deposition amount.

In the present invention, the surface roughness (R _q ) is a numerical value calculated by root mean squared (RMS) of the induced surface state by droplet evolution.

Referring to FIG. 4, it can be seen that the average size of the spontaneously formed Au droplet continuously increases with the gradual increase in the deposition amount of Au on the GaAs (111) ) And the surface line profiles of Figs. 4 (a) and 4 (b).

In one embodiment of the present invention, "AH " means an average height of spontaneously formed Au droplets formed on GaAs (111) B," LD "means an average height of spontaneously formed Au droplets Mean " AD "means the average density of spontaneously formed Au droplets formed on GaAs (111) B.

Referring to the AFM image, line profile, and summary graphs of FIGS. 2-4, it can be seen that the average density is reduced.

For example, as shown in FIG. 2 (a-1), the circular dome-shaped Au droplet was densely packed due to the deposition amount of 2 nm, and the AH of 21.8 nm and the LD of 52 nm, It looked.

The AD of the corresponding Au droplet is measured as 4.48 x 10 ¹⁰ cm ^-2 , as shown in Fig. 4 (c).

Referring to FIGS. 2 (b) and 2 (b-1), when the deposition amount is 2.5 nm, the Au droplet size is 1.44 times the deposition amount of 2 nm with AH of 31.5 nm, , While AD is 1.28 x 10 < ^{10 &} gt ^; cm < 2 & gt ^; , which is 3.5 times the deposition amount of 2 nm.

That is, an increase in the amount of deposition of 0.5 nm resulted in a significant change in size and density, and this change was greater in LD and AD.

Referring to FIGS. 2 (d) and 2 (d-1) and 4, when the deposition amount of 3 nm was further increased by 0.5 nm, the AH of the Au droplet was increased by 1.14 times 35.8 nm, and LD was 1.12 times, 105 nm, and AD was measured to be 7.0 x 10 ⁹ cm ^-2 , which was 1.83 times decreased.

2 (d) and 2 (d-1) and FIG. 4, the droplet continued to increase and the density decreased even at a deposition amount of 4 nm.

Referring to FIGS. 4 (a) and 4 (b), AH of the Au droplet increased by 1.26 times to 45.2 nm and LD to 1.43 times to 150 nm and AD to 2.19 times to 3.2 x 10 < ⁹ > cm ^{< 2} >

That is, it can be seen that AH is increased by 2.07 times, LD is increased by 2.88 times, and AD is decreased by 14 times in the range of 2 nm to 4 nm with increasing deposition amount.

According to an embodiment of the present invention, the desired AD can be controlled by applying a density reduction ratio considering the deposition thickness.

Also, Au droplets can be manufactured by controlling the deposition thickness considering the minimum density.

Further, in order to obtain the desired AH or AD, the AD increase rate of AH considering the deposition thickness or the AH increase rate of AD can be controlled.

Referring to Figures 2 to 4, it can be seen that the size was mainly increased by the diameter expansion and more prominent in the deposition of less than 3 nm from the steep slope of the graphs of Figures 4 (a) and 4 (b).

Au droplets have been shown to be more sensitive to deposition than at lower deposition rates, so deeper attention should be given to high density droplets.

Referring to FIGS. 2 to 4, as the deposition amount increases, the droplet can be formed large and the nanostructure has a lower surface energy because of an increase in surface area. As a result, larger droplets can absorb surrounding adsorbed atoms and tend to become larger until they reach equilibrium. On the other hand, as the size becomes larger, the density tends to decrease.

Figure 4 (d) shows R _q (rms surface roughness) of each sample to measure the change in surface roughness caused by the evolution of spontaneously formed Au droplets.

According to one embodiment of the present invention, _Rq The value provides a direct description of the surface evolution.

Referring to FIG. 4 (d), R _q The value is 3.6 nm due to the small size droplet. At 2.5 nm deposition, the R _q value increased significantly to 10.8 nm, which is three times the value at 2 nm deposition.

This pronounced increase in Rq is due to a sharp increase in the size of the Au droplet as described above (Figures 4a and 4b). At 3 and 4 nm deposition volumes, R _q also continuously increased to 12.8 and 15.3 nm as the droplet size continued to increase.

It can be seen that R _q also increases as the size of the droplet gradually increases with increasing deposition amount.

According to one embodiment of the present invention, to control a desired roughness surface, it is possible to control by applying a roughness surface increase ratio considering the deposition thickness.

 As shown in Figs. 2 (a-1) and 2 (b-1), in Au uniformity of the Au droplet, Au droplets at 2 and 2.5 nm deposition amounts were well grown in a circular shape, and the symmetric circular FFT The pattern was confirmed in Figs. 3 (a-1) and 3 (b-1).

As shown in the AFM images of FIGS. 2 (c-1) and 2 (d-1), Au droplets were observed to be slightly elongated at the deposition amounts of 3 and 4 nm, ) FFT patterns were still symmetrical and circular in shape because they did not exhibit a pronounced tendency to elongation according to a specific crystal orientation.

Figure 5 shows the variation of spontaneously-formed Au drops on GaAs (111) B according to the deposition amount of 6-20 nm according to an embodiment of the present invention.

Figure 6 shows a SEM image of a large area for various deposition amounts.

In general, as described above in the embodiment of FIGS. 2 and 3, it can be seen that the size, including AH and LD of the Au droplet, increases steadily with increasing deposition amount while AD decreases.

According to one embodiment of the present invention, the AH and LD of Au droplets were 55.4 and 196.7 nm and AD was 2.28 x 10 ⁹ cm ^-2 at 6 nm deposition amount ^.

Referring to Figures 5 (a) and 5 (a-1) and the graph of Figure 4, there is a continuous increase in size and a decrease in density.

Referring to FIGS. 5B and 5B-1, at a deposition amount of 9 nm, the AH of the Au droplet was increased to 71.4 nm, the LD was increased to 256.7 nm, and the AD was further reduced to 5.9 × 10 ⁸ cm ^-2 . Compared with the 6 nm deposition amount, the AH and LD increased 1.29 times and 1.31 times, respectively, and the density AD was reduced to 25.9 times as compared with the 6 nm deposition amount.

Referring to Fig. 5 (b-1), it can be seen that a large size is generated.

4 (a) to 4 (c), it can be seen that the super Au drops grow larger and the density decreases at the deposition amounts of 12 and 20 nm. That is, AH = 78.3 and 95.5 nm at 12 and 20 nm deposition amounts; LD = 308.4 and 430 nm; AD = 3.65 x 10 ⁸ and 1.24 x 10 ⁸ cm ^-2 .

According to one embodiment of the present invention, the AH of the super-droplets formed at a deposition amount of 20 nm was increased by 4.38 times, the LD by 8.27 times, and the AD by 361 times compared with the mini-Au drops of the 2 nm deposition amount.

Unlike the growth of Au droplets on Si (111), which is achieved by using Stranski-Krastanov mode, the evolution of Au droplets with a deposition amount of 4.5 nm or more is 6-20 nm Sputtered Au droplets with the increase in the deposition amount evolved based on the Baumer-Weber growth mode (Zhang & Lagally, 1997; Abraham & Newman, 2009) without the formation of long merged Au nanostructures or Au layers.

This may enable the fabrication of super Au droplets with considerable size increase and density reduction.

According to one embodiment of the present invention, R _q Values show a similar tendency to increase (R _q = 19.6 nm at 6 nm and R _q = 23.7 nm at 9 nm), which can be seen to affect R _q due to size expansion.

According to one embodiment of the present invention, showed a significant reduction in the super to the formation of the Au droplet R _q is finally reduced in a deposition amount of 12 and 20 nm (R _q = 22.4 and 19.4 nm) of the density, which is reduced in AD It indicates that the size expansion is exceeded.

The FFT power spectrum of the deposition amount sample of 6 to 20 nm showed a smaller and hazy FFT power spectral pattern due to the lower density. The symmetrical circular pattern indicates that the super-droplet has no selective growth characteristic along any crystal direction.

Referring to FIG. 6, it can be seen from the SEM image of FIG. 6 that the evolution tendency with increase in diameter and decrease in density with increasing deposition amount can be clearly seen even on a large scale. The droplets are uniformly dispersed on the GaAs (111) B surface.

According to an embodiment of the present invention, the spontaneously formed Au droplets formed on the GaAs (111) B are grown in the range of 2 to 20 nm while the growth parameters such as the heat treatment temperature and time are fixed, The height (AH) according to the deposition amount of Au increases to 436% in the range of 21.8 to 95.5 nm, and the average side diameter increases to 827% in the range of 52 nm to 430 nm. Also, the increase in size is the main reason for the side expansion.

On the other hand, the average density (AD) is from time to change the amount of deposited Au in the range of 2 to 20 nm on the GaAs (111) B, 4.48 x 10 10 cm -2 1.24 x 10 < ⁸ >.

In addition, circular dome-shaped mini Au droplets with a high filling density can be produced at relatively low Au deposition quantities of less than 3 nm, whereas at higher deposition quantities above 10 nm, very large Au droplets of several hundred times lower density are produced .

Figs. 7-9 show evolution patterns of spontaneously formed Au droplets on GaAs (110) with increasing deposition amount.

Referring to FIG. 7, it can be seen that the spontaneously-formed Au droplets on the GaAs 110 from the behavior of AH, LD, AD and R _q evolve in a very similar pattern to Au droplets on GaAs (111) B.

Referring to FIG. 7, the AH of the Au droplet increased 1.87 times from 22.7 to 42.5 nm, and the LD increased 2.79 times from 52.8 to 147.1 nm when the deposition amounts to 2 to 4 nm were compared. On the other hand, AD is decreased from 4.48 x 10 ¹⁰ cm ^-2 at 2 nm deposition amount to 13.18 times at 3.4 x 10 ⁹ cm ^-2 at 4 nm deposition amount.

Spontaneously formed Au droplets on the GaAs 110 tend to laterally expand in a decreasing density direction as on GaAs (111) B.

Also, when compared to the deposition of 6-20 nm, the AH increased 1.73 times from 55.8 to 96.7 nm and the LD increased 2.21-fold from 197.5 to 435.7 nm while the AD increased from 1.9 x 10 ⁹ cm ^-2 to 1.12 x 10 ^{8 < / RTI &} gt ^; cm < ² >

As a general comparison, as shown in FIG. 7, while the deposition amount is changed from 2 to 20 nm to 10 times, the AH of the Au droplet is increased by 4.26 times, the LD is increased by 8.25 times, and the AD is decreased by 400 times.

Referring to FIG. 7 (d), similarly, R _q begins to grow at 3.4 nm at a deposition rate of 2 nm and increases continuously during deposition from 2 to 9 nm. At a deposition rate of 9 nm, Lt; / RTI > to 25.0 nm. And thereafter decreases again to a value of 16.1 nm at a deposition amount of 20 nm.

According to one embodiment of the present invention, the average growth rate per 1 nm deposition is 3.086 nm in the range of 2 nm to 9 nm.

And thereafter decreases again to a value of 16.1 nm at a deposition amount of 20 nm.

Thus, according to one embodiment of the present invention, the reduction rate in the range of 9 nm to 20 nm is 0.809 nm per 1 nm deposition.

Referring to FIG. 9, it can be seen that the FFT power spectrum has a small, blurry pattern with a low density drop for a relatively high deposition amount, while having a bright and circular pattern with a relatively high density drop for a relatively low deposition amount.

According to one embodiment of the present invention, the droplet size, including the average height and side diameter, along with the gradual increase in the deposition amount from 2 to 20 nm, continuously increases with the preferred lateral dimension expansion, and the density of the droplet is several hundreds or more It can be seen that it has a gradually decreasing characteristic.

In addition, while a small dome-shaped mini droplet of high density was produced at a deposition amount of 2 to 10 nm in a relatively small deposition amount, a super droplet of AD of 200 nm or more and an AH of 70 nm or more was generated at an deposition amount of 10 nm or more Able to know.

The size and density of the droplets were found to be very sensitive at deposition amounts of less than 3 nm, which can be seen by the magnitude in the low deposition volume region and the steep slope in the R _q graph.

According to an embodiment of the present invention, the AH of the Au droplet increased 1.87 times from 22.7 to 42.5 nm, and the LD increased 2.79 times from 52.8 to 147.1 nm for deposition amounts from 2 nm to 4 nm. On the other hand, AD decreased by 13.18 times from 4.48 x 10 ¹⁰ cm ^-2 at 2 nm deposition to 3.4 x 10 ⁹ cm ^-2 at 4 nm deposition. The spontaneously formed Au droplets on the GaAs (110) are characterized by favoring lateral extension in a decreasing density direction as on GaAs (111) B.

In addition, the AH increased from 55.8 to 96.7 nm by 1.73 times and the LD increased by 2.21 times from 197.5 to 435.7 nm, whereas the AD increased from 1.9 x 10 ⁹ cm ^-2 to 1.12 x 10 ⁸ cm ^{- 2, it} is decreased by 16.96 times.

Referring to FIG. 7, while the deposition amount is changed from 2 to 20 nm to 10 times, the AH of the Au droplet is increased by 4.26 times, the LD is increased by 8.25 times, and the AD is decreased by 400 times.

Also, R _q is 3.4 nm at a deposition rate of 2 nm, from which the deposition rate continues to increase to a peak value of 25.0 nm while increasing from 2 nm to 9 nm. And thereafter tends to decrease to 16.1 nm of the deposition amount of 20 nm.

Referring to the FFT power spectrum of FIG. 9, it has a bright, circular pattern with a relatively high density drop for a relatively low deposition amount, and a small and fuzzy pattern with a low density drop for a relatively high deposition amount. According to one embodiment of the present invention, the evolution of spontaneously formed Au droplets on GaAs (111) B and (110) under a fixed annealing temperature and time proceeds in a Boomer-Weber growth mode.

According to one embodiment of the present invention, the droplet size, including the average height and side diameter, along with the gradual increase in the deposition amount from 2 to 20 nm, continuously increases with the preferred lateral dimension expansion, and the density of the droplet is several hundreds or more It can be seen that it has a gradually decreasing characteristic.

In addition, a circular dome-shaped mini droplet having a density in the range of 1.9 × 10 ⁹ / cm 2 to 4.48 10 ¹⁰ at a relatively small deposition amount of 2 to 6 nm was generated, while a 6.1 × 10 ⁸ ~ 1.12 AU droplets having a low density in the range of 10 ⁸ are formed, and super droplets of AD of 200 nm or more and AH of 70 nm or more are generated.

The size and density of the droplets were found to be very sensitive at deposition amounts of less than 3 nm, which can be seen by the magnitude in the low deposition volume region and the steep slope in the R _q graph.

According to an embodiment of the present invention, the variation element of the pattern according to the variation of the amount of Au deposition described above can be utilized as a growth control method in the manufacturing process according to the deposition of Au by using it as a control factor of Au droplet deposited on GaAs.

According to one embodiment of the present invention, Au droplets having the characteristics of size, density, and surface roughness required by controlling the amount of Au deposition under a heat treatment temperature fixed on GaAs can be manufactured.

10 to 16 illustrate another embodiment of the present invention.

In another embodiment of the present invention, the spontaneously formed Au droplets are grown on a GaAs (111) A, (111) B, (110), and (111) sublayers exhibiting a common zinc blende lattice index in a pulsed laser deposition (PLD) And (100).

The various index samples are indium-bonded together in the Inconel holder for uniformity and are prepared by the process of degassing at 350 ° C for 30 minutes at 1 × 10 ^-4 Torr.

Thereafter, the total amount of Au of 2.5 nm in the ion-coating chamber is equally deposited on the sample at 1 x 10 < ^-1 > Torr by an ionization current of 3 mA at a rate of 0.5 ANGSTROM / s.

In one embodiment of the present invention, in order to investigate the evolution of the spontaneous-formed Au droplet closely, each process was heat-treated at 100, 250, 300, 350, 400, 450, 500, The control characteristics were investigated by systematically varying the characteristics of the annealing process while changing the temperature (Ta).

In one embodiment of the present invention, the substrate temperature Ts was raised to a target temperature at a rate of 1.83 ° C / s under 1 × 10 ^-4 Torr by a computer-controlled recipe, and after reaching each target temperature, The dwell process is performed in the same manner.

Also, after the end of each growth, the substrate temperature is immediately referred to to minimize Ostwald ripening.

FIG. 10 is a graph showing changes in spontaneous-formed Au droplets on GaAs (111) A according to an annealing temperature in the manufacturing process according to an embodiment of the present invention.

10 shows a change pattern in the temperature range of 100 ° C to 550 ° C in the heat treatment temperature of spontaneously formed Au drops on GaAs (111) A.

10 (a) shows a surface AFM side-view image pattern (1 占 1 占 퐉 ² ) of GaAs (111) A before deposition.

10 (b) shows a surface AFM side-view image pattern of GaAs (111) A after 2.5 nm Au deposition

10 (c) shows an AFM side-view image pattern of Au particles formed on the surface of GaAs (111) A after annealing at a temperature of 350 ° C

Referring to Fig. 10 (c), nucleation patterns of wavy Au particles are shown at an annealing temperature of 350 ° C.

FIG. 10 (d) shows an AFM side-view image pattern of Au particles formed on the surface of GaAs (111) A after annealing at a temperature of 550 ° C.

Cross-sectional surface line profiles of (a-1) to (d-1) in Fig. 10 are for the black lines in Figs. 10 (a) to (d).

Referring to FIG. 10, nucleation and wavy Au nanostructures of spontaneously-formed small Au particles appear in various forms on a GaAs (111) substrate.

11 shows the nanostructure of spontaneously formed Au particles on GaAs (111) A induced by a change in the heat treatment temperature (Ta) in the range of 250 < 0 > C to 350 < 0 > C.

Referring to Fig. 11, the AFM top image (1 x 1 탆 ² ) is shown in Figs. 11a, b, c and d along with the cross-sectional line profiles of Figs. 11 (a- b, c, and d.

11 (a-2) to (d-2) show the FFT power spectrum.

The surface morphology of the GaAs (111) A abruptly changes from the relatively planar surface morphology of Fig. 11a, b with increasing annealing temperature Ta and gradually increases with the Au grains of Fig. 12c and the wavy Au nano- Structure.

11, after the Au deposition before the heat treatment, the surface shows a very flat surface as shown in the AFM image of FIG. 11A and the line profile of FIG. 11 (a-1) The FFT spectrum exhibits a very wide circular pattern due to the narrow random surface transformation.

At the heat treatment temperature of 250 ° C, the diffusion of Au adsorbed atoms increased as shown in Fig. 11b, but the surface transformation was only slightly increased as shown by the line profile of Fig. 11 (b-1).

Referring to FIG. 11 (b-2), it can be seen that the FFT spectrum has a smaller circular pattern at a heat treatment temperature of 250 ° C.

Referring to Fig. 11 (c), the diffusion of adsorbed atoms was further increased at an increased heat treatment temperature of 300 ° C, and as a result, as shown in Fig. 11c and (c-1) Generation.

.

Referring to FIG. 11 (d), at the heat treatment temperature of 350 ° C., a sharp transition from the Au particles to the wavy nanostructure as shown in the AFM image of FIG. 11 (d) and the line profile of FIG. 11 It can be seen that it has a height variation pattern of about +/- 10 nm as compared with the line profiles of Figs. 11 (c-1) and (d-1).

The FFT pattern size was reduced by the increased height conversion and became symmetrical because the Au nanostructures had no distinct directionality. The Au particles and the wavy nanostructures can be generated based on the Boomer-Weber growth mode method.

According to one embodiment of the present invention, since the binding energy Ea between Au adsorbing atoms is larger than the binding energy Ei between Au adsorbing atoms and GaAs surface atoms, the Au adsorbing atoms have a relatively low annealing temperature Ta Au nanoparticles can be incorporated to form nuclei of Au and wavy Au nanostructures can be generated at increased Ta.

The transformation of the surface morphology with respect to the nucleation and wavy nanostructures of the Au particles is a unique characteristic on GaAs.

For example, substitution of Si (111) for GaAs has shown that Au particles or wavy Au nanostructures do not appear in the evolution of spontaneously formed Au droplets at a change in the heat treatment temperature of 50 ° C. to 850 ° C. .

In addition, high-density dome-shaped Au droplets were observed over the entire temperature range. A significant transformation of the surface morphology was observed at each annealing temperature (Ta) with increasing annealing temperature (Ta) on GaAs (111) A, and the height transitions were gradually increased with annealing temperature (Ta). Due to the increased diffusion of Au adsorbed atoms induced by increased thermal energy, abrupt transitions were observed with a surface transformation of about +/- 10 nm at 350 占 폚.

Figure 12 shows the evolution pattern of spontaneously formed Au droplets on GaAs (111) A at 400 < 0 > C to 550 < 0 > C heat treatment temperature.

12 (a-2) to 12 (d-2) show the surface line profile, Figs. 12 (a- (d-4) show the height distribution histogram (HDH), respectively. (The Figure 12a, b, c, the enlarged upper surface area of the AFM image 12 to show a large area of 3 × 3㎛ ^2, Fig. (A-1) to (d-1) of d is 1 × 1 ㎛ ² Show me.)

Fig. 13 shows the size and density characteristics of spontaneously formed Au droplets at each annealing temperature (Ta) on a GaAs substrate.

Referring to FIG. 13, FIG. 13A shows a graph of the average height (AH), FIG. 13B shows the side diameter (LD) and FIG. 13C shows the average density AD.

Table 1 summarizes the size and density values of GaAs (111) A, (110), and (100) (111) B.

According to one embodiment of the present invention, spontaneously-formed dome-shaped Au droplets at 400 ° C to 550 ° C have increased thermal energy (bonding energy Ea between Au adsorption atoms> Au adsorption atoms and GaAs surface atoms Due to the increased diffusion of Au adsorbed atoms in the bond energy Ei between the wavy Au nanostructures are preferentially evolved into dome - shaped Au droplets to minimize surface energy.

Referring to Figs. 13A, B and C, in the evolution of size and density, the density decreases with the annealing temperature (Ta) change of GaAs (111) A phase, while the size including AH and LD of Au drops gradually As shown in FIG.

According to one embodiment of the present invention, the Au deposition feature on GaAs produced spontaneously-formed Au droplets at an annealing temperature (Ta) of 400 ° C, and from a wavy Au nanostructure at 350 ° C, a dome- It can be seen that it has a characteristic of changing into a droplet.

According to one embodiment of the present invention, in order to obtain a dome-shaped Au droplet at a low temperature by controlling the annealing temperature to 400 ° C. and forming a wavy Au nanostructure, annealing temperature is set to 350 ° C. , A desired Au nanostructure can be produced.

Referring to Table 1, at 400 캜 annealing temperature, AH is 23.4 nm, LD is 128.6 nm, and AD is 1.39 횞 10 ¹⁰ cm ^-2 .

As shown in Fig. 12 (a-4), the height distribution histograms (HDH) were about ± 15 nm.

Referring to FIG. 13, the Au droplet size was larger and the density was lower at 450 ° C. Referring to Table 1, at 450 ° C, AH increased by 1.09 times to 25.4 nm ×, and LD increased by 1.04 to 133.8 nm. The density decreased by 1.33 times to 1.23 10 ¹⁰ cm ^-2 .

Further, referring to FIG. 12C, the size of the Au droplet is larger and the density is relatively decreased at 500 ° C. At 500 ° C, AH and LD are increased by 1.14 and 1.04 times, respectively, to 28.9 and 138.5 nm, while AD is decreased by 1.04 times to 1.23 × 10 ¹⁰ cm ^-2 . Referring to FIG. 12 (c-4), at 500 ° C, the HDH is further extended to more than ± 20 nm as the size increases.

Referring to FIG. 13, at the heat treatment temperature of 550 캜, the size of the Au droplet continuously increases and the density continues to decrease.

Referring to Table 1, AH and LD are increased by 1.11 and 1.04 times to 32.2 and 143.4 nm, respectively, and the AD is decreased by 1.11 times to 9.9 × 10 ⁹ cm ^-2 at a heat treatment temperature of 550 ° C.

Referring to FIG. 12 (d-4), it can be seen that at a heat treatment temperature of 550 ° C., the HDH clearly spreads more than ± 20 nm as the height of the Au droplet increases.

As shown in the symmetrical circular FFT power spectrum of Figs. 12 (a-3) to (d-3), spontaneously formed Au drops on GaAs (111) A exhibit excellent It can be seen that it has characteristics of uniformity.

As the annealing temperature (Ta) increased, the overall size increased and the density decreased. Annealing Temperature (Ta) Evolution of size and density with temperature change of heat treatment can be explained by the following equation.

(여기서 D는 표면확산계수이고 T는 원자의 잔류시간이다.)으로 표시될 수 있다. 또한, 여기서 [식 2]

로 표현될 수 있다(여기서 T_sb은 기판 온도이며 어닐링 온도(Ta)에 해당한다.)According to an embodiment of the present invention, the diffusion distance l _{D can be} calculated by the following equation (1)

(Where D is the surface diffusion coefficient and T is the residence time of the atom). Further, in the expression (2)

(Where T _sb is the substrate temperature and corresponds to the annealing temperature Ta).

Referring to the above equation, D increases proportionally as the annealing temperature (Ta) increases, which increases (l _D ) when considering the stronger bond energy (Ea> Ei) between the Au atoms. The density of Au droplets can be expressed as decreasing in proportion to the increase in _D.

Figure 14 illustrates the evolution of spontaneously formed Au droplets on GaAs (110) contributed by an annealing temperature (Ta) change in the range of 250 ° C to 550 ° C.

Figures 15 and 7 show the evolution of spontaneously formed Au droplets on GaAs (100) and (111) B. Generally, the evolution of Au droplets on GaAs (110), (100), and (111) B is due to the nucleation and wavy nanostructures of Au particles as shown in FIG. 11, And has a similar phenomenon to the evolution of size and density according to the annealing temperature (Ta) as summarized in the graph of FIG. 13.

Therefore, according to one embodiment of the present invention, the control feature of the evolution process of Au droplets on GaAs (110), (100), and (111) B is similar to the control feature of the evolution process of Au particles on GaAs And the like.

For example, nucleation and wavy Au nanostructures of Au particles on GaAs (110) in the range of 250 ° C to 350 ° C were clearly observed as shown in Figs. 14b, c and d, Of the sputter-formed dome-shaped Au droplets were successfully generated as shown in Figs. 14e, f, g, h. As shown in FIG. 13, the size of the droplet on the GaAs 110 also increased uniformly as the annealing temperature Ta increased, while the density decreased relatively.

While the rate of decreasing density increases from 400 ° C to 550 ° C (111) A

40 × 10 ⁸ cm ^-2 , (110), (100), and (111) B are 41 × 10 ⁸ cm ^-2, which are all reduced at a similar rate.

That is, in the heat treatment temperature of 400 ℃ ~ 550 ℃ range average, the heat treatment temperature is rising every 1 ℃ 26.5 ~ 27.4 × 10 ⁶ ㎝ ^- it can be seen that the decline in the density to ² ratio.

13A, the size of the droplet on the GaAs 110 is slightly smaller than the size of the droplet on the GaAs 111. As shown in FIG. 13C, (111) A The density was slightly higher over the entire temperature range, as shown in line (110) above the line. For example, at 400 ° C, AH, LD, and AD of (110) were 22.6 nm, 122.5 nm, and 1.48 × 10 ¹⁰ cm ^-2 , respectively, which is comparable to AH, LD, and AD of GaAs The size was 3.42% and 4.47% smaller and the density was 6.47% higher. Similarly, the size and density of droplets on (110) at 550 ° C were 31.2 nm (AH), 141 nm (LD), and 1.07 × 10 ¹⁰ cm ^-2 (AD) Compared with AH, LD, and AD, AH was 3.11%, LD was 1.67% smaller, and AD was 8.08% higher. Spontaneously formed Au droplets on GaAs (110) were smaller in size and relatively higher in density than drops of GaAs (111) A over the annealing temperature (Ta) range.

15b, c, d, and 7b, c, and d in accordance with an embodiment of the present invention, nucleation and wavy nano-particles of Au particles on GaAs (100) and (111) The structure was distinctly observed and spontaneously formed Au droplets were generated at 400 ° C to 550 ° C, as shown in Figures 15e, f, g, h and 7e, f, g, h.

Similarly, the size of Au droplets on GaAs (100) and (111) B increased uniformly with increasing annealing temperature (Ta) and density decreased relatively. The surface indices showed a clear difference in size and density between the indices, and this tendency was constant over the entire annealing temperature (Ta) as clearly shown in FIG. For example, GaAs (111) B shows the smallest Au droplet at each annealing temperature (Ta), (111) B at the bottom of graphs (a) and (b) . (110) was increased in size and the largest droplet was generated on GaAs (111) A. In terms of density, GaAs (111) B showed the largest density at each annealing temperature (Ta), followed by (100), (110), and (111) A.

The Miller index [110] of the zinc blende lattice is located at 45 ° from [100] to [010], and these two indices with [111] Quot; index ". As described above, the diffusion distance l _D can be directly related to the annealing temperature Ta, which can affect the size and density of Au droplets. l _D is the surface roughness calculated by root mean squared (RMS) due to several factors such as dangling bond density, atomic step density, and surface reconstruction. (surface roughness, R _q ).

If the R _q value of a surface is lower, the surface may have a longer l _D , which may result in larger Au droplets and lower density.

R _q on GaAs The values are:

(111) A, 0.289 nM; (110), 0.305 nm; (100), 0.322 nM; And (111) B, 0.291 nm.

GaAs (111) A showed the lowest R _q and (110) showed a slight increase. Therefore, referring to Fig. 13, it can be explained that the size of the droplet on the GaAs (111) A is larger and the density is lower.

Similarly, the increased _Rq May be associated with a decrease in the size of Au drops on the GaAs (100) and an increase in density, as compared to Au drops on (110) having a value of. However, the (111) B surface showed R _q similar to (111) A, showing the smallest and largest density.

Type-A GaAs surfaces have Ga-rich properties while Type-B surfaces have As-rich properties.

Based on the atomic model of the Au-GaAs interface, the Ga-rich surface can have higher interface energy than the As-rich surface. Thus, the reduced diffusion of Au atoms on the Type-B surface can cause a lower l _D and can represent the size of smaller droplets with larger densities.

According to one embodiment of the present invention, since the evolution of spontaneously formed Au droplets on various GaAs surfaces exhibits different characteristics in terms of size and density depending on the annealing temperature, Au nanostructures of desired characteristics can be manufactured have.

According to one embodiment of the present invention, it can be seen that the nucleation step of native Au particles and wavy nanostructures is formed on various GaAs surfaces in the Ta range of 250 ° C to 350 ° C.

Also, according to one embodiment of the present invention, spontaneously-formed dome-shaped Au drops having excellent uniformity are produced at 400 ° C to 550 ° C, and the average height and side diameter of the Au drops gradually increase And the average density is relatively decreased at each Ta point.

According to an embodiment of the present invention, GaAs (111) A> (110)> (100)> (111) B are sequentially arranged over the entire range of Ta in terms of size and diameter.

In one embodiment of the present invention, it has been experimentally tried to change the heat treatment temperature after deposition of 2.5 nm Au. Repeated experiments with different thicknesses have shown that the deposition thickness can be obtained at any thickness in the range of 2 to 20 nm.

According to one embodiment of the present invention, the pattern change factor according to the above-described heat treatment change can be utilized as a growth control method in the manufacturing process according to the Au deposition by using the change factor as the control factor of the Au droplet deposited on the GaAs. That is, Au droplets having the size and density characteristics required by controlling the heat treatment temperature under the deposition amount fixed on GaAs can be produced.

Claims (12)

A method of depositing Au on a GaAs substrate by sputtering under vacuum plasma ion deposition chamber by Pulsed laser deposition,
Wherein at least one of an average height, a side diameter, a density and a surface roughness of the deposited Au droplet is controlled by a heat treatment temperature or an Au deposition amount in the deposition process. Growth control method The method according to claim 1,
Controlled by the heat treatment temperature,
Wherein the Au deposition amount is controlled to a target temperature in the range of 100 to 550 ° C. after depositing the Au deposition amount to a predetermined thickness of 2 nm to 20 nm, 3. The method of claim 2,
Controlled by the heat treatment temperature,
Wherein the control is performed using a characteristic that the average height and the side diameter are increased and the density is decreased when the heat treatment temperature is raised.
The method of claim 3,
Wherein the diffusion distance (I _D ) associated with the side diameter is calculated by the following equation: < EMI ID =

(Where D is the surface diffusion coefficient, T is the residence time of the atom, and T _sb is the annealing temperature Ta) 5. The method of claim 4,
Wherein the density is decreased in proportion to an increase in the diffusion distance (I _D ). The method according to claim 1,
Wherein the annealing temperature is controlled in the range of 400 ° C to 550 ° C so as to form the deposited Au droplets having a dome-like characteristic having uniformity. The method of claim 1, wherein
Wherein the annealing temperature is controlled in a range of 250 ° C to 250 ° C so as to form the surface of the deposited Au droplet so as to have a wavy nanostructured characteristic.
The method of claim 1, wherein
Controlled by the heat treatment temperature,
Characterized in that the density is controlled in the range of 26.5 to 27.4 x 10 < ⁶ > cm & lt ^{; 2} > at the temperature of the heat treatment in the range of 400 DEG C to 550 DEG C each time the heat treatment temperature is increased by 1 DEG C, Control method
The method according to claim 1,
Controlled by the amount of Au deposition,
Wherein the Au deposition amount is controlled in a range of 2 to 20 nm, and then controlled in a PLD chamber under a vacuum of less than 1 x 10 ^-4 Torr at a temperature of 823 K, including a heat treatment process. Control method
The method according to claim 1,
Controlled by the amount of Au deposition,
The surface roughness is increased by an increase rate of 3.086 nm per 1 nm Au deposition (in which the surface state is a value calculated by the root mean square) when the Au deposition amount is in the range of 2 nm to 9 nm, and when the Au deposition amount exceeds 20 nm Wherein the surface roughness is controlled by a characteristic of decreasing the average of 0.809 nm per 1 nm deposition (the surface state is a value calculated by the root mean square)
The method according to claim 1,
Controlled by the amount of Au deposition,
A circular dome-shaped mini droplet having a density in the range of 1.9 × 10 ⁹ / cm 2 to 4.48 10 ^{10 is produced in the} range of the Au deposition amount of 2 to 6 nm, and 6.1 × 10 ⁸ ~ 1.12 × 10 ⁸ droplets grow larger Au Au droplet on a GaAs substrate, characterized in that for controlling the density using the characteristics to be formed having a low density in the range of the control method The method according to claim 1,
Controlled by the amount of Au deposition,
When the Au deposition amount is changed from 2 nm to 20 nm, the average height of the Au droplets to be formed is increased by 4.26 times to the average height of the deposition amount of 2 nm, and the side diameter of the Au droplet is 8.25 Wherein the GaAs substrate is grown on a GaAs substrate by using an Au growth control method

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