Black Silicon Germanium (SiGe) for Extended Wavelength 

Near Infrared Electro-optical Applications

by Fred Semendy, Patrick Taylor,

Gregory Meissner, and Priyalal Wijewarnasuriya

ARL-TR-5202 May 2010

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Army Research Laboratory

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ARL-TR-5202 May 2010

Black Silicon Germanium (SiGe) for Extended Wavelength 

Near Infrared Electro-optical Applications

Fred Semendy, Patrick Taylor,

Gregory Meissner, and Priyalal Wijewarnasuriya

Sensors and Electron Devices Directorate, ARL

Approved for public release; distribution unlimited.
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Black Silicon Germanium (SiGe) for Extended Wavelength Near Infrared Electrooptical Applications

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Fred Semendy, Patrick Taylor, Gregory Meissner, and Priyalal Wijewarnasuriya

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14. ABSTRACT

We have investigated for the first time the reflectivity and absorbance of black silicon-germanium (Si1-xGex). Black Si1-xGex

was produced by metal enhanced chemical etching using nanometer-scale gold particles as catalyst and HF:H2O2:CH3COOH 

etchant. The etched surface was black, textured, and showed strong suppression of reflectivity and enhancement of absorption 

in the near-infrared region. These properties are consistent with Si1-xGex becoming highly micro-structured due to metal 

catalysis and wet etching. The lowering of reflection and enhancement of absorption in Si1-xGex is an important milestone 

towards practical, extended wavelength (~2 μm) electro-optical applications.

15. SUBJECT TERMS

SiGe, Black, texturing, optical properties, infrared, compositional

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Fred Semendy

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iii

Contents

List of Figures iv

1. Introduction 1

2. Experimental Details 2

3. Results and Discussion 4

4. Conclusion 10

5. References 11

List of Symbols, Abbreviations, and Acronyms 13

Distribution List 15
iv

List of Figures

Figure 1. Experimental procedure for the nano catalyst formation on the SiGe surface.................3

Figure 2. Etch rate of Si1-xGex in HF:H2O2:CH3COOH (1:2:3). .....................................................4

Figure 3. Pictures of AFM roughness measurements for sample (a) Si0.85Ge0.15, (b) Si0.70Ge0.30, 

and (c) Si0.50Ge0.50. ....................................................................................................................5

Figure 4. %R of unetched and etched (a) Si0.85Ge0.15, (b) Si0.70Ge0.30, and (c) Si0.50Ge0.50..............6

Figure 5. Absorbance of thinned Si1-xGex samples after lapping and polishing. .............................7

Figure 6. Absorbance spectrum of etched and unetched samples of (a) Si0.85Ge0.15, 

(b) Si0.70Ge0.30, and (c) Si0.50Ge0.50.............................................................................................8

Figure 7. The surface texture pattern of the sample Si0.85Ge0.15. .....................................................9

Figure 8. The surface texture pattern of the sample Si0.70Ge0.30. .....................................................9

Figure 9. The surface texture pattern of the sample Si0.50Ge0.50. ...................................................10
1

1. Introduction

Over the past 10 years, new phenomena based on nanostructuring the surface of silicon (Si) have 

been investigated for application to infrared imaging. In 2003, Mazur and colleagues reported 

that using femtosecond laser processing coupled with halogenated etching gas, silicon surfaces 

having sub-micrometer corrugated conical tip microstructures could be produced (1). These 

microstructures had the special property that the surface of the silicon was rendered almost 

perfectly non-reflective. They named this material “black silicon.” In that early study, they 

showed that when they produced that microstructure using only halogenated etching gas (sulfur 

hexafluoride [SF6]) the spectral absorbance of light was extended well beyond that which would 

be expected from conventional band-theory understanding of silicon. In subsequent reports from 

researchers in the Mazur group, evidence began to point to the very highly doped surface region 

(sulfur-doped) on the etched surface that seemed to promote sub-bandgap absorption (2). In that 

work, they showed the important result that after forming the etched surface, the extended 

wavelength infrared absorbance could be decreased and almost completely eliminated because of 

dopant evaporation during high-temperature annealing.

Based on these early results, the Mazur Group partnered with device researchers at the 

University of Virginia and the University of Texas at Austin to demonstrate a novel infrared 

detector based on this new material (3).

The researchers in this partnership showed two very important demonstrations: (1) the spectral 

responsivity was enhanced compared to that of conventional silicon photodetectors and

(2) responsivity was obtained at longer infrared wavelengths (1.3 and 1.55 μm), beyond the

spectral range generally expected from silicon, which is limited to about 0.85 μm. While there is 

some uncertainty about the mechanism that enables sub-bandgap, longer wavelength detection, 

the mechanism is currently explained as longer wavelength photons excite carriers across the 

energy difference between mid-gap defect states from the heavily doped region and the 

conduction band edge. While the science behind the phenomena is being resolved, these 

interesting results presage new, low-cost near-infrared detectors that could have important 

military and civilian applications. However, for tactical military applications, a much higher 

spectral response at extended wavelengths in the near-infrared (~2 μm) would be desired. To that 

end, we are investigating silicon-germanium (Si1-xGex) materials with the goal of obtaining an 

improved photo response out to 2 μm by (1) shrinking the bandgap so that the difference between 

the conduction band-edge and the defect state is reduced and (2) providing a naturally larger 

absorption coefficient for longer wavelength light. So this work builds upon the results reported 

from the Mazur and partner groups and investigates new heavily doped black Si1-xGex materials.

Some important differences between this work and the approach of the Mazur and partner groups 

are (1) we employ a metal-masked, wet-chemical etching approach versus a femtosecond gas-
2

phase etching process and (2) we used in-situ boron doping p≈5x1019/cm3 versus sulfur doping 

n≈5x1020/cm3 from the past work. 

Our investigation with black Si1-xGex is very important since SiGe is a good substitute material 

for Si for many applications in low-power and high-speed semiconductor device technologies 

(4, 5). It is a promising material for quantum well devices (6), infrared detectors (7), and 

modulation doped field-effect transistors (MODFET) (8, 9). Recently, much work has been 

planned to use Si1-xGex for optodetectors and micro-electro-mechanical systems (MEMS) sensors 

and actuators. Activity is also being continued to develop flip chip optical receives. Among the 

many other applications currently being considered are strained SiGe on silicon to be used as 

base in a heterojunction bipolar transistor (HBT) in a bipolar complementary metal oxide 

semiconductor (BiCMOS) process and complementary metal oxide semiconductor (CMOS)

logic applications. SiGe has much to offer for the fabrication of devices with improved 

efficiency (10). In a particular instance, self assembled Ge-islands and black Ge based on nanoneedle arrays have been developed (11). 

Increased absorption of light is essential to create highly efficient opto-sensors and photovoltaic 

devices. To achieve this, efficient three-dimensional (3-D) structures with relevant material 

systems are required. Apart from these two techniques, others (12, 13) have proposed a 

technique in which multicrystalline SiGe bulk crystal with microscopic compositional 

distribution is grown using the casting technique. The average Ge composition was changed 

systematically between 0% and 10%. A small addition of Ge to multicrystalline Si was found to 

be very effective to increase the short-circuit current density without affecting open circuit 

voltage. They also indicated that such grown SiGe materials are promising candidates for solar 

cell and other opto-electronic applications. For such applications, SiGe has to be prepared with 

reduced reflectivity and increased absorbance. This can be achieved through surface texturing, as 

has been used in the case of black silicon. In general, for a 3-D blackened surface, reactive ion 

etching or wet anisotropic etching are the techniques of choice. Although reactive ion etching 

can provide a structure with a high aspect ratio, it involves rather complicated procedures. Metal 

enhanced etching (MEE) (14, 15), by which silicon is etched using metal thin films or particle as 

catalysts, is an attractive procedure because it is simple and easier to perform with good results. 

2. Experimental Details

The SiGe layers in this work were grown on 8-in high-resistance (111) silicon substrates using a 

special ultra-high vacuum chemical vapor deposition (UHV-CVD) reactor. Three planar SiGe 

alloys were prepared: Si0.50Ge0.50, Si0.70Ge0.30, and Si0.85Ge0.15. The thickness of all SiGe layers 

was about 1.25 μm. Using such a large thickness assures that although some small residual strain 

probably exists after growth, the large misfit strain is mostly relaxed through the introduction of 

dislocations. In order to avoid strain induced surface undulations in such highly compressively 
3

strained layers, the SiGe were grown at 350–400 °C. Although UHV-CVD growth allows highly 

perfect crystalline quality with little impurity incorporation even with growth rates as low as 

10–3

Å/s, we have intentionally doped all layers of this study to achieve near-degenerate p-type 

doping. Hall effect characterization yielded the typical result that p = 3.47x1020/cm3

. The 

Seebeck coefficient was determined to be 28x10–6 V/K and is consistent with the neardegenerate doping level. There was some variation in the measured Hall mobility, but the range 

was always <100cm2/V-s because of alloy-scattering and scattering from dislocations and 

ionized impurities. In this experiment, test samples mole fractions of 0.15, 0.30, and 0.50 Ge 

were used. Cleaned samples were used for atomic force microscopy (AFM), and the 

spectroscopic percent reflection (%R) and percent transmission (%T) measurements. Another set 

of samples were cleaned and loaded into the e-beam evaporator. The pressure in the evaporator 

was maintained below 1x10–6 mTorr gold (Au) was evaporated of at a rate 0.1 Ǻ per second to 

attain a thickness of 20 Ǻ. The samples were then annealed in a rapid thermal annealing (RTA)

system for 30 min at 500 °C with argon (Ar) gas flow. These steps are shown in figure 1.

Figure 1. Experimental procedure for the nano catalyst formation on the SiGe surface.

The samples were inspected using AFM to make sure nanoparticles of Au are randomly oriented 

on the surface of Si1-xGex. In the next part of the experiment, a set of samples without Au were 

etched in solution of HF:H2O2:CH3COOH (1:2:3) with masking to find the etch rate. Care was 

takeN to wait 30 min prior to using this etchant. The etching of the samples in the above solution 

showed linearity in the etch rate and proceeded to darkened surface. Once the etch rate was 

determined for different compositions of Si1-xGex, etching was carried out with a newly prepared 

solution of HF:H2O2:CH3COOH (1:2:3) without additional masking. After etching in that

solution as part of the texturing process, the samples were thoroughly cleaned and blowdried 

with nitrogen. The solution etched Si1-xGex while slowly preserving the surface polish. However, 

etching the samples for more than 10 min showed visible damage. Finally, the etched samples 

were dipped in an aqueous solution of iodine (I) and potassium iodide (KI) (25 gm I and 100 gm 

KI per liter of water [H2O] ) (16). The samples were further cleaned in running de-ionized water 

and dried with nitrogen. These samples were further used for AFM surface analysis and optical 

reflection and transmission measurements using a Perkin Elmer 950 UV-Visible-Near IR 

spectrometer.

20 A gold deposition by 

e- beam evaporation Si <111>

Si1-xGex

Anneal at 500

C, 30min, and 

A Si <111>

Si1-xGex

Si <111>

Si1-xGex

Gold Nano Gold 
4

3. Results and Discussion

All the samples were cleaned and surface characterized using AFM prior to the experiment.

Some of the samples were thinned by lapping and polishing using a Logitech 10 System. Here 

the goal was to make sure that the samples under consideration were double-side polished to 

reduce the specular reflections. Samples were cleaned, and 20 Ǻ of Au was deposited on the 

Si1-xGex surface in an e-beam evaporator, which was kept at a pressure lower than 1x10–6 mTorr.

Small pieces of these samples with appropriate masking were etched with HF:H2O2:CH3COOH 

(1:2:3), which was freshly prepared and left at room temperature for 30 min for stabilization 

before use. Etching was done at room temperature (25 °C) in polypropylene beakers with slight 

agitation. The samples were 1 cm2 in area in area in ~100 ml of fresh solution of

HF:H2O2:CH3COOH (1:2:3). Figure 2 shows the etching behavior of 

Si1-xGex in HF:H2O2:CH3COOH (1:2:3).

Figure 2. Etch rate of Si1-xGex in HF:H2O2:CH3COOH (1:2:3).

The linear etching behavior is clearly evident from the Ge concentration in the Si1-xGex. The 

rapid increase in etch rate can be explained by the presence of an increased number of Ge surface 

atoms. The bonding energy reveals the difficulty in breaking the Si-Si bonds (compared to Ge-Si 

and Ge-Ge bonds) is 78 kcal/mol; the Ge-Si bond dissociation energy is 72 kcal/mol and the 

Ge-Ge bond dissociation energy is 65 kcal/mol (17). The more Ge-Ge and Ge-Si bonds are 

exposed, the higher the etching rate is, as can be seen from the graph. The etched surface 

provided a greyish blackened surface.

The goal of finding the reduction in reflectivity and an increase in absorption was pursued as the 

next step. Etched and non-etched samples of size 1 by 1 cm were used for the optical 

measurements. Samples were cleaned with acetone and isopropal alcohol (IPA), followed by 

blow drying with nitrogen. The samples after thermal annealing were used for optical and AFM 

surface measurements. The AFM scanned surface plot is given in two cases in figure 3.
5

Figure 3. Pictures of AFM roughness measurements for sample (a) Si0.85Ge0.15, (b) Si0.70Ge0.30, and 

(c) Si0.50Ge0.50.

The scanned area was 2 μm and the root mean squared (rms) values obtained in all three cases 

were as follows: sample 1 (Si0.85Ge0.15) ~37–18 nm, sample 2 (Si0.70Ge0.30 ) ~40.94 nm, and 

sample 3 (Si0.50Ge0.50) ~203.9 nm. Clearly, the rms value increases as the amount of Ge 

increases; the sample numbers from 1 to 3 clearly indicate the nature of the surface. Since the 

contour of the Au nanoparticle surface mimics the real surface, it certainly indicates the 

progressive nature of the roughness as the amount of Ge increases in the sample. 

Optical measurements were performed as follows. After measuring the %T and %R, we used the 

equation, A = 1 – T - R, to obtain the absorbance. Unetched, etched, thinned, and annealed 

samples were used for the measurement of %T and %R, which we then applied to the above 

formula to calculate the percent absorbance. The results etched and unetched samples are plotted 

in figure 4. The spectrum shows the reflectivity behavior of a thin film―the thickness being 

~1.6 μm of the Si1-xGex layer on the Si (111) substrate.
6

Figure 4. %R of unetched and etched (a) Si0.85Ge0.15, 

(b) Si0.70Ge0.30, and (c) Si0.50Ge0.50. 

The spectrum shows considerable reduction in reflectivity for Si1-xGex samples after etching, as 

can be seen in figure 4.

(a)

(b)

(c)
7

As can be observed from the plots, the reflectivity goes through substantial reduction after the 

etching. The reflectivity reduces by ~85% for samples by MEE especially in the IR region. This 

lowering of reflectivity is a definite indication of surface modification with micro-structure 

formation due to the wet etch processing.

Nano texturing of a surface depends on a number of factors, including the nature and constituent 

of the etchant, time of etching, and the metal catalyst. In many other cases when etching silicon, 

catalysts such as Ag, palladium (Pd), copper (Cu), and platinum (Pt) have given good results.

This current work is the first time a metal enhanced wet etching was attempted with 

HF:H2O2:CH3COOH (1:2:3) as the etching solution for nano texturing of Si1-xGex. The observed 

optical effects can be explained by the formation of nanoscale textures on the Si1-xGex surface, 

representing an effective medium with a smooth transition of the refractive index from air to 

SiGe (18). In another experiment, as indicated earlier, samples were thinned by lapping and 

polished to make the reflection losses minimum. Such thinning and polishing lets the wafer to be 

double-side polished, thus minimizing reflection losses. Using the thinned samples, %R and %T

were measured to calculate absorbance and the absorbance values are plotted in figure 5. 

Figure 5. Absorbance of thinned Si1-xGex samples after lapping and polishing.

The un-thinned Si1-xGex samples were used for wet etching, as indicated earlier, using the etchant 

HF:H2O2:CH3COOH (1:2:3). The etchant was prepared and left at room temperature for ~30 min 

and the previously cleaned samples with Au nanoparticles were submerged for various times. To 

obtain appreciable darkness on the surface of samples, etching was done for about 15 min.

Samples were retrieved and cleaned in running de-ionized H2O to remove all the acid from the 

surface. This was followed by dipping in a solution containing KI-I2 complex commercially 

available as Gold Etchant TFA/GE-8148 from Transene, Inc (20). This step was followed by 

cleaning the samples in running de-ionized H2O for 5 min, followed by blow drying them using 

nitrogen. These samples were used for optical characterization to obtain %T and %R.

Absorbance was calculated using the equation A = 1 – T - R. The absorbance versus the 
8

wavelength is plotted in figure 6. The plots include the absorbance for the unetched and etched 

samples in each case. In all three cases, one can see that the absorbance went up, indicating the 

reflectivity decreased even though the %T remained the same.

Figure 6. Absorbance spectrum of etched and unetched samples of 

(a) Si0.85Ge0.15, (b) Si0.70Ge0.30, and (c) Si0.50Ge0.50.

(a)

(b)

(c)
9

In general, the absorbance increase is from 5–10%, the larger increase being in Si0.85Ge0.15. The 

etched samples were further characterized using a Veeco surface topography profiler. The 

system’s white light interferometry can measure surface topography from nanometer-scale 

roughness through millimeter-scale steps, with a sub-nanometer resolution. This surface

metrology system was used to understand the surface texture patterns and parameters of the 

etched surface. Figure 7 gives the surface texture pattern of the sample Si0.85Ge0.15. The curves

on the right indicate the x-axis (red) and y-axis (blue), as indicated on the middle cross wire.

Figure 7. The surface texture pattern of the sample Si0.85Ge0.15.

Figures 8 and 9 give the surface texture pattern of Si0.70Ge0.30 and Si0.50Ge0.50, respectively.

Texturing is prominent in the third sample and sample Si0.50Ge0.50 and, correspondingly, the rms 

value is higher as well. In figure 9, one can see more damage and separation of regions in 

Si1-xGex due to wet etching.

There may be also formations of clustered Ge regions on the surface. This argument can be 

justified by the x-y plot on the right side in figure 9, unlike in figure 7 and 8, where the x-y plots 

are spaced closely. 

One of the reasons for this behavior is the presence of a lower amount of Si in Si1-xGex and a 

higher amount of Ge.

Figure 8. The surface texture pattern of the sample Si0.70Ge0.30.
10

Figure 9. The surface texture pattern of the sample Si0.50Ge0.50.

4. Conclusion

We reported here for the first time an investigation of optical properties of reflection and 

absorbance of compositional Si1-xGex semiconductor alloys after treating with metal enhanced 

chemical etching using nano-sized Au particles as the catalyst and HF:H2O2:CH3COOH as the 

etchant. The etched surface became black, textured, and showed a suppression of reflectivity and 

an enhancement of absorption in the near-infrared region. Conceivably, the black Si1-xGex

became micro-structured due to the metal catalysis and wet etching. Surface texturing was 

visible, as shown by the plots, and became extreme in the case of Si0.55Ge0.45. Visible separation 

in the x-y plots positively indicates this behavior, which is due to the lower amount of Si and an

excess amount of Ge in Si1-xGex. Through this work, we have shown that Si1-xGex can be made 

black using metal enhanced chemical etching. We have also shown that such black Si1-xGex has

reduced reflectivity and enhanced absorbance in the near-infrared region.

Detectors made with this type of black Si1-xGex will have higher performance in the extended IR 

region. This lowering of reflection and enhancement of absorption may have important practical

implications for making efficient photovoltaic and photodetecting applications using 

compositional Si1-xGex alloys. Currently, we are fabricating photodetectors to prove our 

conclusion.
11

5. References

1. Younkin, R.; Carey, J.; Mazur, E.; Levinson, J.; Friend, C. J. Appl. Phys. 2003, 93 (5), 2626.

2. Crouch, C.; Carey, J.; Shen, M.; Mazur, E.; Genin, F. Appl. Phys A 2004, 79, 1635.

3. Huang, Z.; Carey, J.; Liu, M.; Guo, X.; Mazur, E.; Campbell, J. Appl. Phys. Lett. 2006, 89, 

033506.

4. Konig, U.; Gruhle, A. Proceedings of the 1997 IEEE/Cornell Conference on Advanced 

Concepts in High Speed Semiconductor Devices and Circuits, IEEE, Ithaca, NY, 1997.

5. Grimmeiss, H. G. Semiconductors 1999, 33, 939.

6. Nayak, D. K.; Woo, J. C.; Park, J. S.; Wang, K. L.; MacWilliams, K. P. IEEE Electron

Device Lett. EDL-12-154 1991.

7. Luryi, S.; Kastalsky, A.; Bean, J. C. IEEE Trans. Electron Devices ED-31 1984, 1135.

8. Perasall, T. P.; Bean, J. C. IEEE Electron Device Lett. EDL-7 1986, 308.

9. Venkataraman, V.; Liu, C. W.; Strum, J. C. J. Vac. Sci. Technol 1993, B 11, 1176.

10. Williamson, D. L. Solar Energy Materials and Solar Cells 2003, 78 (1–4), 41–84.

11. Chueh, Y. L.; Fan, Z.; Takei, K.; Ko, H.; Kapadia, R.; Rathore, A. A.; Miller, N.; Yu, K.; 

Wu, M.; Haller, E. E.; Javey, A. Nano Lett. 2010, 10, 520.

12. Koynov, S.; Brandt, M. S.; Stutzmann, M. App. Phys. Lett. 2006, 88, 203107.

13. Wu, C.; Crouch, C. H.; Zhao, L.; Carey, J. E.; Yonkin, R.; Levinson, J. A.; Mazur, E.;

Farrell, R. M.; Gothoskar, P.; Karger, A. App. Phys. Lett. 2001, 73, 1850.

14. Nakajima, K.; Usami, N.; Fujiwara, K.; Murakami, Y.; Ujihara, T.; Sazaki, G.; Shishido, T.

Sol. Energy Mater. Sol. Cells 2002, 72, 93.

15. Nakajima, K.; Usami, N.; Fujiwara, K.; Murakami, Y.; Ujihara, T.; Sazaki, G.; Shishido, T.

Sol. Energy Mater. Sol. Cells 2002, 73, 305.

16. Li, X.; Boh, P. W. Appl. Phys. Lett. 2000, 77, 2572.

17. Yee, S.; Kawamoto, Y.; Tanaka, H.; Fukumuro, N.; Matsuda, H. Elechem. Comm. 2003, 5, 

632.

18. Schumb, W. C.; Satterfield, C. N.; Wentworth, R. L. in Hydrogen Peroxide, Reinhold 

Publishing, New York, 1955, p. 370.
12

19. Kishioka, K.; Horita, S.; Ohdaria, K.; Matsumura, H. Sol. Energy Mater. Sol. Cells 2008, 92, 

919.

20. Transene Company Web page. http://www.transene.com/au_etchant.html (accessed 2010).
13

List of Symbols, Abbreviations, and Acronyms

%R percent reflection 

%T percent transmission 

3-D three-dimensional 

AFM atomic force microscopy 

Ar argon 

Au gold

BiCMOS bipolar complementary metal oxide semiconductor 

CMOS complementary metal oxide semiconductor 

Cu copper 

Ge germanium

H2O water

HBT heterojunction bipolar transistor 

I iodine 

IPA isopropal alcohol 

KI potassium iodide 

MEE metal enhanced etching 

MEMS micro-electro-mechanical systems 

MODFET modulation doped field-effect transistors 

Pd palladium 

Pt platinum 

rms root mean squared 

RTA rapid thermal annealing 

SF6 sulfur hexafluoride

Si silicon 
14

Si1-xGex silicon-germanium

UHV-CVD ultra-high vacuum chemical vapor deposition
15

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ATTN RDRL SE E L BLISS

ATTN RDRL SE E T BOWER

ATTN RDRL SED E M LITZ

ATTN RDRL SED P A LELIS

ATTN RDRL SED P B MORGAN

ATTN RDRL SED P K JONES

ATTN RDRL SEE G WOOD

ATTN RDRL SEE P GILLESPIE

ATTN RDRL SEE E T ALEXANDER

ATTN RDRL SEE E K ALIBERTI

ATTN RDRL SEE E N GUPTA 

ATTN RDRL SEE E R TOBER

ATTN RDRL SEE I S TRIVEDI

ATTN RDRL SEE I B ZANDI

ATTN RDRL SEE I D BEEKMAN

ATTN RDRL SEE I F SEMENDY 

(5 COPIES)

ATTN RDRL SEE I G BRILL

ATTN RDRL SEE I J LITTLE

ATTN RDRL SEE I K K CHOI
16

NO. OF

COPIES ORGANIZATION

ATTN RDRL SEE I K OLVER

ATTN RDRL SEE I P FOLKES

ATTN RDRL SEE I P TAYLOR

ATTN RDRL SEE I P UPPAL

ATTN RDRL SEE I S FARRELL

ATTN RDRL SEE I S SVENSSON 

ATTN RDRL SEE I W BECK

ATTN RDRL SEE I W SARNEY

ATTN RDRL SEE I Y CHEN

ATTN RDRL SEE M G DANG

ATTN RDRL SEE M G GARRETT

ATTN RDRL SEE M M REED

ATTN RDRL SEE M 

M TAYSING-LARA

ATTN RDRL SEE M M WRABACK

ATTN RDRL SEE M N BAMBHA

ATTN RDRL SEE M N DAS

ATTN RDRL SEE M P SHEN

ATTN RDRL SEE M W CHANG

ATTN RDRL SEE O N FELL 

ATTN RDRL SEE O P PELLEGRINO

ATTN RDRL SEG N MARK

ATTN RDRL SER E A DARWISH

ATTN RDRL SER E P SHAH

ATTN RDRL SER L A WICKENDEN

ATTN RDRL SER L B NICHOLS

ATTN RDRL SER L E ZAKAR

ATTN RDRL SER L M DUBEY

ATTN RDRL SER L M ERVIN

ATTN RDRL SER L S KILPATRICK

ATTN RDRL SER P AMIRTHARAJ

ATTN RDRL SER U C FAZI

ADELPHI MD 20783-1197

TOTAL: 71 (69 HCS, 1 CD, 1 ELECT)