Thank you for posting your request on History Hub!
The "official" photos of individuals are not considered to be permanent federal records by the respective military services and are not retained in a separate collection by the service. If the photo you are seeking still exists, it will most likely be found in the individual's Official Military Personnel File (OMPF). However, there is no guarantee the photo will be present.
OMPFs of those who served in the U.S. Army during the Vietnam War are located at NARA's National Personnel Records Center, (Military Personnel Records), 1 Archives Drive, St. Louis, MO 63138-1002. Please complete a GSA Standard Form 180 to request these records.
Another possibility is the series Photographs of U.S. Army Operations in Vietnam, 1963 – 1973 which has now been fully digitized and available in our catalog.
If there was an awards ceremony, there is a slight possibility that it is included with the Army Signal Corps photographs taken during the Vietnam War. For access to this collection, please contact the National Archives at College Park - Still Picture (RDSS) via email at firstname.lastname@example.org and their web site is https://www.archives.gov/dc-metro/college-park/photographs-dc.html.
Please keep in mind that due to the COVID-19 pandemic and pursuant to guidance received from the Office of Management and Budget (OMB), NARA has adjusted its normal operations to balance the need of completing its mission-critical work while also adhering to the recommended social distancing for the safety of NARA staff. As a result of this re-prioritization of activities, you may experience a delay in receiving an initial acknowledgement as well as a substantive response to your reference request. We apologize for this inconvenience and appreciate your understanding and patience.
Some sources outside of the National Archives that you might want to try are local newspaper archives from that time period. Most local public libraries offer access to newspaper archives, indexes and morgues with your library card. There are also quite a few records available on Ancestry and Family Search. NARA has partnered with these groups to help digitize and make available quite a few military records. Family Search does not require a subscription and can be accessed with a free account. Ancestry does require a subscription, but many public libraries offer free access with your library card.
We hope this information is helpful. Good luck with your research.